Control system for secondary battery

Abstract

To provide a control system for a secondary battery which performs temperature control of a secondary battery and is less affected by an environmental temperature.SOLUTION: A control system for a secondary battery which is less affected by an environmental temperature by performing temperature control is realized using a plurality of kinds of secondary batteries and loaded on a vehicle. Specifically, in a case where the environmental temperature is low, a part of a second secondary battery is heated using self-heating of a first secondary battery, and after the second secondary battery is sufficiently heated, the remaining part of the second secondary battery is heated step by step using self-heating of a part of the second secondary battery in which a temperature is increased. Whether or not a part of or the whole of the second secondary battery is sufficiently heated is determined by providing a plurality of temperature sensors in the second secondary battery, and their temperatures only need to fall within a usage temperature range of the second secondary battery. For example, the temperature sensor uses a temperature detection terminal (T terminal) and when an internal temperature of the secondary battery is out of the usage temperature range, a switch is closed.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a secondary battery and a method for manufacturing the same. Or, it relates to a vehicle or the like having a secondary battery.

[0002] One aspect of the present invention relates to an article, a method, or a manufacturing method. Or, the present invention relates to a process, a machine, a manufacture, or a composition of matter. One aspect of the present invention relates to a semiconductor device, a display device, a light-emitting device, a power storage device, a lighting device, an electronic device, or a method for manufacturing them.

[0003] In this specification, the electronic device generally refers to all devices having a power storage device, and all electro-optical devices having a power storage device and information terminal devices having a power storage device are electronic devices.

[0004] In this specification, the power storage device generally refers to an element and a device having a power storage function. For example, it includes a power storage device (also referred to as a secondary battery) of a lithium-ion secondary battery, a lithium-ion capacitor, and an electric double layer capacitor.

Background Art

[0005] In recent years, various power storage devices such as lithium-ion secondary batteries, lithium-ion capacitors, and air batteries have been actively developed. In particular, lithium-ion secondary batteries with high output and high energy density are rapidly expanding in demand along with the development of the semiconductor industry, for portable information terminals such as mobile phones, smartphones, or notebook computers, portable music players, digital cameras, medical devices, or next-generation clean energy vehicles such as hybrid vehicles (HV), electric vehicles (EV), or plug-in hybrid vehicles (PHV), and have become indispensable in modern information society as a source of repeatedly rechargeable energy.

[0006] Lithium-ion secondary batteries have problems with charging and discharging in low-temperature or high-temperature conditions. In particular, since secondary batteries are power storage means that utilize chemical reactions, it is difficult to exhibit sufficient performance at low temperatures below freezing. Also, lithium-ion secondary batteries may have a shortened lifespan and there is a risk of abnormalities occurring at high temperatures.

[0007] Regardless of the operating environment as a secondary battery, a battery that can exhibit stable performance is desired.

[0008] Also, a technology for a protection circuit that controls the charging current according to the ambient temperature, which reduces the charging current when the temperature is low by utilizing the temperature characteristics of a transistor using an oxide semiconductor (hereinafter referred to as an OS transistor), is disclosed in Patent Document 1.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0010] One of the problems is to provide a control system for a secondary battery that controls the temperature of the secondary battery and is less affected by the ambient temperature. Another problem is to provide a highly safe monitoring system for secondary batteries.

[0011] Also, one of the problems is to detect abnormalities in the secondary battery, for example, to detect early a phenomenon that reduces the safety of the secondary battery and to warn the user to ensure safety.

Means for Solving the Problems

[0012] A control system for a secondary battery that is less affected by environmental temperature is realized by using a plurality of types of secondary batteries and performing temperature control, and is mounted on a vehicle. Specifically, when the environmental temperature is low, the power of the first secondary battery is used to heat a part of the second secondary battery. After the second secondary battery is sufficiently heated, a part of the second secondary battery with an increased temperature is used to gradually heat the remaining part of the second secondary battery. Whether a part or all of the second secondary battery is sufficiently heated can be determined by providing a plurality of temperature sensors in the second secondary battery and ensuring that their temperatures are within the operating temperature range of the second secondary battery. For example, when the internal temperature of the secondary battery is outside the operating temperature range using a temperature detection terminal (T terminal), the switch closes.

[0013] The first secondary battery itself serves as a heat source for warming up a part of the second secondary battery. Therefore, the first secondary battery is for low temperatures and uses a type of secondary battery that can discharge at low temperatures. After raising the temperature of a part of the second secondary battery by self-heating of the low-temperature secondary battery, a part of the second secondary battery that has become dischargeable due to the temperature rise serves as a heat source for warming up the remaining secondary battery.

[0014] Also, the lower limit of the operating temperature range of the first secondary battery is lower than the lower limit of the operating temperature range of the second secondary battery. The first secondary battery and the second secondary battery use different types of secondary batteries. For example, the electrolytes of the first secondary battery and the second secondary battery are different. Also, a semi-solid battery may be used for the first secondary battery, and an electrolyte may be used for the second secondary battery.

[0015] Depending on the materials or configurations used, there are an operating temperature range and a storage temperature range for safely using the secondary battery. The storage temperature range is wider than the operating temperature range. In this specification, the operating temperature range refers to the temperature range suitable for using the secondary battery, that is, the temperature range at which it is normally used (during discharge). Also, the operating temperature range during discharge may be different from the operating temperature range during charging. The storage temperature range is an appropriate temperature range that can suppress the degree of deterioration of the secondary battery when neither discharging nor charging and the charge control circuit is stopped.

[0016] The configuration disclosed in this specification includes a first lithium-ion secondary battery having a first temperature range as the operating temperature range, a second lithium-ion secondary battery having a second temperature range including the upper limit of the first temperature range as the operating temperature range, and a temperature sensor for detecting the temperature of the second lithium-ion secondary battery. The lower limit of the first temperature range is lower than the lower limit of the second temperature range. When the temperature of the temperature sensor is lower than the second temperature range, there is a control circuit that self-heats and heats the first lithium-ion secondary battery to bring the temperature of the second lithium-ion secondary battery within the second temperature range. This is a vehicle with such a control circuit.

[0017] In the above configuration, the lower limit of the first temperature range is at least less than 25°C, and the upper limit of the second temperature range is at least higher than the first temperature range.

[0018] If the operating temperature range of the secondary battery is from -40°C to 85°C, it can be said to be an ideal secondary battery. However, considering the materials used (specifically, the electrolyte), it is difficult to realize a secondary battery that discharges or charges at -40°C to 85°C. Therefore, in the present invention, by using multiple types of secondary batteries with different operating temperature ranges, a control system for a secondary battery that is less affected by the ambient temperature can be realized. For example, a first lithium-ion secondary battery with an operating temperature range of -40°C to less than 25°C and a second lithium-ion secondary battery with an operating temperature range of 0°C to 85°C, preferably 25°C to 85°C are used. The first lithium-ion secondary battery with an operating temperature range of -40°C to less than 25°C can be called a secondary battery for low temperatures, and it functions as a power source for the heating means of the second lithium-ion secondary battery at low temperatures. Also, since the secondary battery for low temperatures has an auxiliary role, the capacity of the second lithium-ion secondary battery is larger, and the second lithium-ion secondary battery functions as the main power source (main battery).

[0019] In each of the above configurations, the first lithium-ion secondary battery may be an all-solid-state battery or a semi-solid-state battery.

[0020] As used herein, a semi-solid battery refers to a battery having a semi-solid material in at least one of an electrolyte layer, a positive electrode, and a negative electrode. The term "semi-solid" here does not mean that the ratio of the solid material is 50%. "Semi-solid" means having some properties of a liquid such as flexibility while having properties of a solid such as small volume change. As long as these properties are satisfied, it may be a single material or a plurality of materials. For example, it may be a liquid material infiltrated into a porous solid material. For example, a polymer electrolyte secondary battery may be referred to as a semi-solid battery. A polymer electrolyte secondary battery includes a dry (or true) polymer electrolyte battery and a polymer gel electrolyte battery.

[0021] In addition, the secondary battery control system disclosed in this specification includes a first lithium-ion secondary battery, a second lithium-ion secondary battery having a different operating temperature range from the first lithium-ion secondary battery, heating means for heating the second lithium-ion secondary battery, a monitoring circuit for monitoring the voltage and temperature of the second lithium-ion secondary battery, and a control circuit electrically connected to the monitoring circuit. A switch is provided between the heating means and the first lithium-ion secondary battery, and the switch is a secondary battery control system controlled by the control circuit.

[0022] In the above control system, it is preferable that the monitoring circuit or the control circuit has a protection circuit. The protection circuit has a cut-off switch or a diode to prevent over-discharge, over-charging, or over-current. Further, the protection circuit may have a function of detecting an abnormality of a micro-short. Specifically, a protection circuit for detecting an abnormality of a micro-short samples (acquires) the potential between the positive and negative electrodes of the secondary battery at predetermined time intervals during charge and discharge of the secondary battery, and compares the sampled potential with the potential between the positive and negative electrodes after sampling, thereby detecting an instantaneous potential fluctuation (here, the potential drops) due to a micro-short.

[0023] A micro short circuit refers to a minute short circuit inside a secondary battery. It does not mean that the positive and negative electrodes of the secondary battery are short circuited and it becomes impossible to charge and discharge. Instead, it refers to a phenomenon where a short circuit current flows for a short period through a minute short circuit part. The cause of the micro short circuit is presumed to be that when charging and discharging are performed multiple times, metal elements such as lithium or cobalt are deposited inside the battery, and as the deposits grow, local current concentration occurs between a part of the positive electrode and a part of the negative electrode, resulting in a location where a part of the separator stops functioning, or side reaction products are generated.

[0024] Also, each of the plurality of secondary batteries has a monitoring circuit. The monitoring circuit (monitoring circuit) of the secondary battery monitors the voltage or temperature of the secondary battery. The monitoring circuit of the secondary battery is electrically connected to a control circuit. The control circuit has a charging control circuit and restricts the charging current or the discharging current when the voltage or temperature exceeds the upper limit value or falls below the lower limit value. The control circuit has a circuit for determining the charging conditions of the secondary battery. Also, the control circuit uses a CPU (Central Processor Unit) or a GPU (Graphics Processing Unit). Also, the control circuit can also use an APU (Accelerated Processing Unit), which is a chip integrating a CPU and a GPU into one. Also, an AI (IC incorporating a system, also called an inference chip) may be used. The IC incorporating an AI system may also be called a circuit (microprocessor) that performs neural network processing.

[0025] Also, in the case of a low temperature below the freezing point, it preferably has a control circuit that switches from the normal mode to the preheating mode and raises the temperature of the secondary battery by heating means until it is within the usable temperature range.

[0026] Further, the monitoring circuit may have a protection circuit. Further, a protection circuit may be provided in the control circuit. Further, the charge control circuit may be a separate IC chip from the control circuit. Further, the charge control circuit may be composed only of an OS transistor, or only a part of the configuration may be composed of an OS transistor. Further, the cutoff switch of the protection circuit may be composed of a transistor having single crystal silicon or the like. Further, the control circuit may be formed of a material having Ge (germanium), SiGe (silicon germanium), GaAs (gallium arsenide), GaAlAs (gallium aluminum arsenide), InP (indium phosphide), SiC (silicon carbide), ZnSe (zinc selenide), GaN (gallium nitride), GaOx (gallium oxide; x is a real number greater than 0). A configuration using silicon in which the effective mass is controlled by applying stress to the crystal lattice and changing the lattice spacing may also be used.

[0027] Further, heating means may be provided, and the configuration includes a first lithium ion secondary battery having a first temperature range as the use temperature range, a second lithium ion secondary battery having a second temperature range including the upper limit of the first temperature range as the use temperature range, a temperature sensor for detecting the temperature of the second lithium ion secondary battery, and heating means for heating the second lithium ion secondary battery. The heating means is electrically connected to the first lithium ion secondary battery, the lower limit of the first temperature range is lower than the lower limit of the second temperature range, and when the temperature of the temperature sensor is lower than the second temperature range, it is a vehicle having a control circuit for heating the second lithium ion secondary battery to be within the second temperature range by heating means powered by the first lithium ion secondary battery.

[0028] Furthermore, a configuration in which three or more secondary batteries are sequentially heated by a heater is also one aspect of the present invention. The configuration includes a first lithium-ion secondary battery having a first temperature range as the operating temperature range, a second lithium-ion secondary battery having a second temperature range including the upper limit of the first temperature range as the operating temperature range, a first temperature sensor for detecting the temperature of the second lithium-ion secondary battery, a first heating means for heating the second lithium-ion secondary battery, a third lithium-ion secondary battery having the second temperature range as the operating temperature range, a second temperature sensor for detecting the temperature of the third lithium-ion secondary battery, and a second heating means for heating the third lithium-ion secondary battery. The first heating means is electrically connected to the first lithium-ion secondary battery, the second heating means is electrically connected to the second lithium-ion secondary battery, the lower limit of the first temperature range is lower than the lower limit of the second temperature range, and when the temperature of the second secondary battery is lower than the second temperature range, it is heated by the first heating means, and after the temperature of the second lithium-ion secondary battery is brought within the second temperature range, the second secondary battery has a control circuit that functions as a power source for the second heating means for heating the third lithium-ion secondary battery.

[0029] In the above configuration, it is preferable that the first lithium-ion secondary battery has a control circuit that functions as a power source for heating the second lithium-ion secondary battery.

[0030] In each of the above configurations, the melting point of the electrolyte of the first lithium-ion secondary battery is preferably -40°C or lower, and at least the main component of the electrolyte of the first lithium-ion secondary battery is preferably composed of a component having a melting point of -40°C or lower.

[0031] Also, in each of the above configurations, it is preferable that the viscosity of the electrolyte of the second lithium-ion secondary battery is lower than the viscosity of the electrolyte of the first lithium-ion secondary battery.

[0032] When providing a heating means for heating the secondary battery, either a heater structure of a resistance heating method using electric heat by passing an electric current through a nichrome wire, a resistor such as ceramics, or a heater structure of a dielectric heating method in which a heater is built into a catalyst and heated with electrical energy, or a plurality of them can be used. For example, a ceramic heater or a film heater may be arranged in the vicinity of the secondary battery. Also, a configuration may be adopted in which the secondary battery is sandwiched or surrounded by a plurality of heating means.

Advantages of the Invention

[0033] By preparing a secondary battery for low temperatures as an auxiliary power source and providing a heating means for heating a part of the secondary battery of the main power source, it is possible to provide a control system for the secondary battery that is less affected by the ambient temperature. Even when the outside temperature is -40°C or higher and less than 25°C, the vehicle can be moved by heating a part of the secondary battery of the main power source with the secondary battery for low temperatures. Also, even when the temperature is 25°C or higher and 85°C or lower, the vehicle can be moved using the secondary battery of the main power source.

[0034] In addition, since each of the secondary batteries has a temperature sensor, it is possible to detect an abnormality in the secondary battery, for example, detect at an early stage a phenomenon that reduces the safety of the secondary battery, and warn the user, thereby ensuring safety.

Brief Description of the Drawings

[0035]

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Mode for Carrying Out the Invention

[0036] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following description, and it is easily understood by those skilled in the art that its form and details can be variously changed. Further, the present invention is not to be construed as limited to the description content of the embodiments shown below.

[0037] (Embodiment 1) In the present embodiment, an example will be described below in which the temperature of the secondary battery 11a is increased using the low-temperature secondary battery 10 at low temperatures, and after the temperature has risen, the temperature of the secondary battery 11b is increased using the secondary battery 11a, and in order, the temperatures of 11c, 11d, and 11e are increased.

[0038] FIG. 1 is a conceptual diagram showing one aspect of the present invention.

[0039] The secondary battery 10 for low temperature is an auxiliary power source, and the main power source is the secondary batteries 11a, 11b, 11c, 11d, 11e connected in series. Although not shown, it has a monitoring circuit (monitoring circuit) having a temperature sensor respectively. The secondary batteries 11a, 11b, 11c, 11d, 11e are secondary batteries having the same configuration. In FIG. 1, a total of 5 examples are shown for simplicity of explanation, but it is not particularly limited. A plurality of secondary batteries used in a vehicle are connected in series or in parallel, and 100 or more are mounted, and in many cases, about 6,500 are mounted on one vehicle. In the case of a large vehicle such as a truck or a bus, more secondary batteries are mounted.

[0040] Further, the viscosity of the electrolyte used in the secondary batteries 11a, 11b, 11c, 11d, 11e is preferably lower than the viscosity of the electrolyte used in the secondary battery 10 for low temperature. The viscosity can be measured by a rotational viscometer.

[0041] As the secondary battery 10 for low temperature, a lithium ion secondary battery having a lower limit of the use temperature range of -40 ° C or more and less than 25 ° C, preferably -40 ° C or more and less than 0 ° C is preferable. Specifically, as the electrolyte, a mixture of ethylene carbonate (EC) as a cyclic carbonate material and dimethyl carbonate (DMC) or ethyl methyl carbonate (EMC) as a chain carbonate material can be used. It has been confirmed that a secondary battery using this combination of electrolytes can be charged and discharged at -40 ° C and 0.1C. Further, polypropylene carbonate (PC) or fluoroethylene carbonate (FEC) may be used instead of EC. Further, these cyclic carbonates may be mixed and used at an arbitrary ratio. Alternatively, a semi-solid battery or an all-solid battery may be used as the secondary battery 10 for low temperature.

[0042] The melting point of ethylene carbonate (EC) is 38°C, the boiling point is 238°C, and the viscosity (viscosity at 40°C) is 1.9 cP (at 40°C). The melting point of dimethyl carbonate (DMC) is 3°C, the boiling point is 90°C, and the viscosity is 0.59 cP. The melting point of ethyl methyl carbonate (EMC) is -54°C, the boiling point is 107°C, and the viscosity is 0.65 cP. The melting point of polypropylene carbonate (PC) is -50°C, the boiling point is 242°C, and the viscosity is 2.5 cP. The melting point of fluoroethylene carbonate (FEC) is 17°C, and the boiling point is 210°C. It is preferable that at least the main component of the electrolyte layer used in the secondary battery 10 for low temperature is composed of components having a melting point of -40°C or lower. The main component refers to 1 wt% or more of the entire electrolyte layer, and less than 1 wt% is regarded as an impurity. Also, the composition of the solvent used in the electrolyte layer may be determined using NMR (nuclear magnetic resonance) or GC-MS (gas chromatography-mass spectrometry). It is more desirable that one of the electrolytes (also called solvents and electrolytic solutions) used in the secondary battery for low temperature is EMC, which exhibits a melting point of at least -40°C or lower.

[0043] In addition, additives such as vinylene carbonate, propane sultone (PS), tert-butylbenzene (TBB), fluoroethylene carbonate (FEC), lithium bis(oxalate) borate (LiBOB), and dinitrile compounds such as succinonitrile and adiponitrile may be added to the electrolyte layer. The concentration of the additive may be, for example, 0.1 wt% or more and 5 wt% or less based on the entire solvent.

[0044] As the secondary batteries 11a, 11b, 11c, 11d, 11e, lithium-ion secondary batteries with a wide operating temperature range including high temperatures are preferable. Specifically, as the electrolyte, a mixture of diethyl carbonate (DEC) and ethylene carbonate (EC) is used. The melting point of diethyl carbonate (DEC) is -43°C, the boiling point is 127°C, and the viscosity is 0.75 cP. The secondary batteries 11a, 11b, 11c, 11d, 11e have reduced characteristics when used below the freezing point, but those with high capacity and less deterioration at high temperatures are used.

[0045] In addition, the operating temperature range of the secondary battery 10 for low temperatures and the operating temperature ranges of the secondary batteries 11a, 11b, 11c, 11d, and 11e overlap at least partially.

[0046] Conventionally, there has been a system in which an electric vehicle is connected to an external charging stand and the entire secondary battery is simultaneously heated during charging. There has also been a system for simultaneously adjusting the temperature of the entire secondary battery of an electric vehicle to be constant.

[0047] In this embodiment, at low temperatures, a part of the main power source, for example, only the secondary battery 11a, is heated by the secondary battery 10 for low temperatures. After heating, the secondary battery 11a that has been heated and can be used is used as a heat source to heat the secondary battery 11b. In this way, the remaining secondary batteries are sequentially made usable, and the entire secondary battery is sequentially heated. In order to heat by self-heating of the secondary battery 10 for low temperatures, it is preferable to arrange the secondary battery 10 for low temperatures near the secondary battery 11a. Also, in order to heat the secondary battery 11b using the secondary battery 11a as a heat source, it is preferable to arrange the secondary battery 11a and the secondary battery 11b close to each other. In FIG. 1, it is a diagram in which each is arranged, but it is not particularly limited. Actually, the secondary battery 10 for low temperatures may be arranged under the bottom surface of the secondary battery 11a, and the secondary battery 11b may be arranged in contact with the side surface of the secondary battery 11a. Also, a configuration may be adopted in which heat is easily conducted by arranging a member with high thermal conductivity between the secondary batteries. For example, by using a material with high heat transfer rate, such as copper or aluminum, for the housing of the secondary battery, heat can be sufficiently conducted even if the secondary batteries are arranged slightly apart from each other.

[0048] The secondary battery group of the vehicle is managed by a control circuit including a CPU, the voltage of the secondary battery is monitored, and the charging conditions during charging and the discharging conditions during discharging are controlled. The control circuit has a protection circuit for preventing overcharging or over-discharging. In this embodiment, each secondary battery has a temperature sensor, and in addition to the electrical characteristics of the voltage, the temperature is also monitored, and the system can control the temperature of the secondary battery.

[0049] Next, the sequence of the preheating mode of the temperature control system of the secondary battery at low temperature is shown below with reference to an example of the flowchart in FIG. 2.

[0050] First, the temperature is measured using the temperature sensor provided in the secondary battery 11a. When the temperature is lower than the operating range of the secondary battery 11a, the control circuit stops charging and discharging. The control circuit switches from the normal mode to the preheating mode and starts the preheating mode.

[0051] The low-temperature secondary battery 10 can function as a heat source by being energized. The switch that controls the energization on and off of the low-temperature secondary battery 101 can also be said to be a temperature control circuit. The control circuit controls the switch and, if the temperature of the secondary battery 11a is low, uses the self-heating of the low-temperature secondary battery 10 for heating. (S1)

[0052] Next, the secondary battery 11a reaches the operable temperature due to the heat (self-heating) of the low-temperature secondary battery 10. (S2)

[0053] Next, heating is performed using the secondary battery 11a as a heat source by energizing the secondary battery 11a. (S3)

[0054] Next, the secondary battery 11b reaches the operable temperature due to the heat of the secondary battery 11a. (S4)

[0055] Next, heating is performed using the secondary battery 11b as a heat source. (S5)

[0056] Next, the secondary battery 11c reaches the operable temperature due to the heat of the secondary battery 11b. (S6)

[0057] Next, heating is performed using the secondary battery 11c as a heat source. (S7)

[0058] Next, the secondary battery 11d reaches the operable temperature due to the heat of the secondary battery 11c. (S8)

[0059] Next, heating is performed using the secondary battery 11d as a heat source. (S9)

[0060] Next, due to the heat of the secondary battery 11d, the secondary battery 11e reaches the operable temperature. (S10)

[0061] By the above procedure, even at low temperatures, the secondary batteries 11a, 11b, 11c, 11d, and 11e can be efficiently heated to the operable temperature by performing sequential heating. When all the secondary batteries 11a, 11b, 11c, 11d, and 11e are heated to the operable temperature, the control circuit switches from the preheating mode to the normal mode and ends the preheating mode.

[0062] Also, although FIG. 1 shows an example of a total of six secondary batteries, one low-temperature secondary battery and five serially connected secondary batteries, the number of secondary batteries is not particularly limited as long as it is two or more, and a configuration of a total of three secondary batteries, one low-temperature secondary battery and two parallel-connected secondary batteries, can also be adopted.

[0063] (Embodiment 2) In this embodiment, an example using a heater is shown. By using a heater, the low-temperature secondary battery 101 can be placed in the dashboard that is less affected by the external environment, and the secondary batteries 102a, 102b, 102c, 102d, and 102e can be placed under the vehicle interior, specifically under the seat, and can be placed at positions away from each other. The main power source that adds weight is preferably placed under the vehicle interior when giving priority to the vehicle's weight balance. When placed under the vehicle interior, it is close to the ground and close to the outside air, so it is likely to get cold in cold regions, but the low-temperature secondary battery 101 placed in the dashboard that is less affected by the external air enables stable motor startup. An example of raising the temperature of the secondary battery 102a using the low-temperature secondary battery 101 at low temperatures and then raising the temperature of the secondary battery 102b using the secondary battery 102a after the temperature has risen will be described below.

[0064] FIG. 3 is a conceptual diagram showing one aspect of the present invention.

[0065] The secondary battery 101 for low temperatures is an auxiliary power source, and the main power source is the secondary batteries 102a, 102b, 102c, 102d, 102e connected in series. Also, although not shown, it has a monitoring circuit (monitoring circuit) having a temperature sensor respectively. Further, it has heaters 150a, 150b, 150c, 150d, 150e for heating the secondary batteries 102a, 102b, 102c, 102d, 102e. The secondary batteries 102a, 102b, 102c, 102d, 102e are secondary batteries with the same configuration. In FIG. 3, five examples in total are shown for simplicity of explanation, but it is not particularly limited. A plurality of secondary batteries used in a vehicle are connected in series or in parallel, and 100 or more are mounted, and in many cases, about 6,500 are mounted on one vehicle. In the case of large vehicles such as trucks or buses, even more secondary batteries are mounted.

[0066] Also, the viscosity of the electrolyte used in the secondary batteries 102a, 102b, 102c, 102d, 102e is preferably lower than the viscosity of the electrolyte used in the secondary battery 101 for low temperatures.

[0067] As the secondary battery 101 for low temperatures, a lithium-ion secondary battery with a lower limit of the operating temperature range of -40°C or more and less than 25°C, preferably -40°C or more and less than 0°C, is preferred. Specifically, as the electrolyte, a mixture of ethylene carbonate (EC) as a cyclic carbonate material and dimethyl carbonate (DMC) or ethyl methyl carbonate (EMC) as a chain carbonate material can be used. It has been confirmed that a secondary battery using this combination of electrolytes can be charged and discharged at -40°C and 0.1C. Also, polypropylene carbonate (PC) or fluoroethylene carbonate (FEC) may be used instead of EC. Also, these cyclic carbonates may be mixed and used at any ratio. Alternatively, a semi-solid battery or an all-solid battery may be used as the secondary battery 101 for low temperatures.

[0068] Incidentally, the melting point of ethylene carbonate (EC) is 38°C, the boiling point is 238°C, and the viscosity (viscosity at 40°C) is 1.9 cP. Also, the melting point of dimethyl carbonate (DMC) is 3°C, the boiling point is 90°C, and the viscosity is 0.59 cP. Further, the melting point of ethyl methyl carbonate (EMC) is -54°C, the boiling point is 107°C, and the viscosity is 0.65 cP. Also, the melting point of polypropylene carbonate (PC) is -50°C, the boiling point is 242°C, and the viscosity is 2.5 cP. Further, the melting point of fluoroethylene carbonate (FEC) is 17°C and the boiling point is 210°C. It is preferable that at least the main component of the electrolyte layer used in the secondary battery for low temperature is composed of a component having a melting point of -40°C or lower.

[0069] In addition, additives such as vinylene carbonate, propane sultone (PS), tert-butylbenzene (TBB), fluoroethylene carbonate (FEC), lithium bis(oxalate) borate (LiBOB), and dinitrile compounds such as succinonitrile and adiponitrile may be added to the electrolyte layer. The concentration of the additive may be, for example, 0.1 wt% or more and 5 wt% or less based on the entire solvent.

[0070] As the secondary batteries 102a, 102b, 102c, 102d, 102e, lithium ion secondary batteries in a wide operating temperature range including high temperatures are preferable. Specifically, as the electrolyte, a mixture of diethyl carbonate (DEC) and ethylene carbonate (EC) is used. The melting point of diethyl carbonate (DEC) is -43°C, the boiling point is 127°C, and the viscosity is 0.75 cP. The secondary batteries 102a, 102b, 102c, 102d, 102e have reduced characteristics when used below the freezing point, but those with high capacity and less deterioration at high temperatures are used.

[0071] Also, the operating temperature range of the secondary battery 101 for low temperature and the operating temperature ranges of the secondary batteries 102a, 102b, 102c, 102d, 102e overlap at least partially.

[0072] Conventionally, there has been a system that connects an electric vehicle to an external charging stand and simultaneously heats the entire secondary battery during charging. There has also been a system that simultaneously adjusts the temperature of the entire secondary battery of an electric vehicle to a constant value.

[0073] In this embodiment, at low temperatures, a part of the main power supply, for example, only the secondary battery 102a, is heated by the heater 150a. After heating, the switch 103a is turned off, and the heater 150a is stopped from heating. Next, the heater 150b powered by the secondary battery 102a that has been heated and made usable is heated to heat the secondary battery 102b. In this way, the remaining secondary batteries are sequentially made usable, and the entire secondary battery is heated.

[0074] The secondary battery pack of the vehicle is managed by a control circuit including a CPU, the voltage of the secondary battery is monitored, and the charging conditions during charging and the discharging conditions during discharging are controlled. The control circuit has a protection circuit to prevent overcharging or over-discharging. In this embodiment, each secondary battery has a temperature sensor, and in addition to the electrical characteristics of the voltage, the temperature is also monitored, and the temperature of the secondary battery can be controlled by a heater.

[0075] Also, the sequence of the preheating mode of the temperature control system of the secondary battery at low temperatures is shown below with reference to an example of the flowchart in FIG. 4.

[0076] First, the temperature is measured using the temperature sensor provided in the secondary battery 102a. When the temperature is lower than the usable range of the secondary battery 102a, the control circuit stops charging and discharging. The control circuit switches from the normal mode to the preheating mode and starts the preheating mode.

[0077] Even when it is said to be low temperature, there are almost no cold regions where the secondary battery is lower than -40°C. Since the low-temperature secondary battery 101 arranged inside the vehicle dashboard is at a temperature higher than -40°C, the low-temperature secondary battery 101 is within the usable temperature range.

[0078] The secondary battery 101 for low temperature can function as a power source for the heater 150a, and the switch for controlling the on / off of the heater 150a can also be said to be a temperature control circuit. The control circuit controls the switch 103a and heats it with the heater 150a if the temperature of the secondary battery 102a is low. (S11)

[0079] Next, the secondary battery 102a reaches the usable temperature by heating with the heater 150a. (S12) When the temperature sensor of the secondary battery 102a reaches, for example, 25°C, the control circuit turns off the switch 103a.

[0080] Next, the control circuit turns on the switch 103b and heats the heater 150b using the secondary battery 102a as a power source. (S13)

[0081] Next, the secondary battery 102b reaches the usable temperature by heating with the heater 150b. (S14) When the temperature sensor of the secondary battery 102b reaches, for example, 25°C, the control circuit turns off the switch 103b.

[0082] Next, the control circuit turns on the switch 103c and heats the heater 150c using the secondary battery 102b as a power source. (S15)

[0083] Next, the secondary battery 102c reaches the usable temperature by heating with the heater 150c. (S16) When the temperature sensor of the secondary battery 102c reaches, for example, 25°C, the control circuit turns off the switch 103c.

[0084] Next, the control circuit turns on the switch 103d and heats the heater 150d using the secondary battery 102c as a power source. (S17)

[0085] Next, the secondary battery 102d reaches the usable temperature by heating with the heater 150d. (S18) When the temperature sensor of the secondary battery 102d reaches, for example, 25°C, the control circuit turns off the switch 103d.

[0086] Next, the control circuit turns on switch 103e and heats heater 150e using secondary battery 102d as a power source. (S19)

[0087] Next, due to the heating of heater 150e, secondary battery 102e reaches the usable temperature. (S20) When the temperature sensor of secondary battery 102e reaches, for example, 25°C, the control circuit turns off switch 103e.

[0088] By the above procedure, even at low temperatures, by sequentially performing heating, secondary batteries 102a, 102b, 102c, 102d, and 102e can be efficiently heated to the usable temperature. When all of secondary batteries 102a, 102b, 102c, 102d, and 102e are heated to the usable temperature, the control circuit switches from the preheating mode to the normal mode and ends the preheating mode.

[0089] Although the above procedure and FIG. 4 show the flow at the start of the electric vehicle at low temperatures, since the temperatures of secondary batteries 102a, 102b, 102c, 102d, and 102e can always be monitored, when the temperature of any one of the secondary batteries drops during driving and is likely to go out of the usable temperature range, the control circuit turns on an appropriate switch to selectively heat the heater, and the temperature of the secondary battery can be kept within the usable range. Therefore, with the above configuration, precise temperature management of a plurality of secondary batteries can be performed. Since some of the plurality of secondary batteries may partially cool down, it can be detected by the control circuit and only that part can be selectively heated.

[0090] Also, although FIGS. 1 and 3 show an example of a total of six secondary batteries, one low-temperature secondary battery and five series-connected secondary batteries, it is not particularly limited, and a configuration of a total of three secondary batteries, one low-temperature secondary battery and two parallel-connected secondary batteries, can also be adopted.

[0091] FIG. 5 is a diagram showing an example of a block diagram of the entire electric vehicle.

[0092] The electric vehicle shown in Fig. 5, which is an electric car, has a first secondary battery 1311 as a secondary battery for low temperatures and second and third secondary batteries 1301a and 1301b as main secondary batteries. The secondary battery for low temperatures may be arranged inside the dashboard, and the main secondary batteries may be arranged under the vehicle interior.

[0093] As the secondary battery for low temperatures, the first secondary battery 1311 is connected to a heater 1308a that heats the second secondary battery 1301a via a switch 1322. The switch 1322 may be a relay circuit. Instead of directly connecting the first secondary battery 1311 and the heater 1308a, it may also be via a DCDC circuit 1310. In this embodiment, a configuration using a heater is adopted. However, when self-heating is used as in Embodiment 1, it is arranged at a position where the second secondary battery 1301a can be heated by the self-heating of the first secondary battery 1311, and at a position where the third secondary battery 1301b can be heated by the self-heating of the second secondary battery 1301a, then the heater is unnecessary.

[0094] Also, the first secondary battery 1311 is electrically connected to a control circuit 1302 via a monitoring circuit 1321. The monitoring circuit 1321 includes a temperature sensor and is a circuit that monitors temperature or voltage.

[0095] A monitoring circuit 1320a is also connected to the second secondary battery 1301a, and a monitoring circuit 1320b is also connected to the third secondary battery 1301b. In this embodiment, an example in which the second secondary battery 1301a and the third secondary battery 1301b are connected in two parallel is shown, but they may be connected in three or more parallel. By configuring a battery pack having a plurality of secondary batteries, a large amount of power can be taken out. The plurality of secondary batteries may be connected in parallel, in series, or may be connected in parallel first and then further connected in series. The plurality of secondary batteries are also called a battery assembly.

[0096] The first secondary battery 1311 is a secondary battery for low temperatures that can be used even at low temperatures as compared with the second secondary battery 1301a or the third secondary battery 1301b, and uses different types of lithium ion batteries. For example, they can be made different by varying the electrolyte. The first secondary battery 1311 may use a semi-solid battery.

[0097] Also, the first secondary battery 1311 only needs to be able to heat the second secondary battery 1301a with the heater 1308a, and a large capacity is not so necessary. The capacity of the first secondary battery 1311 may be smaller as compared with the second secondary battery 1301a or the third secondary battery 1301b. For example, they can be made different by varying the cathode materials of the first secondary battery 1311 and the second secondary battery 1301a.

[0098] When the ambient temperature is below freezing, the control circuit 1302 turns on the switch 1322, and the first secondary battery 1311 supplies power to the heater 1308a to heat the second secondary battery 1301a. Then, if the monitoring circuit 1320a can confirm that the second secondary battery 1301a has reached the operating temperature range, the control circuit 1302 turns on the switch 1323 and heats it with the heater 1308b powered by the second secondary battery 1301a, and the monitoring circuit 1320b monitors until the third secondary battery 1301b is within the operating temperature range. The second secondary battery 1301a and the heater 1308b may be connected not directly but via the DCDC circuit 1306.

[0099] Also, after raising the temperature of the second secondary battery 1301a to reach the operating temperature range, the third secondary battery 1301b may be heated by both the heater 1308a and the heater 1308b.

[0100] The control circuit 1302 supplies power to the inverter 1312 that obtains power from any one of the first secondary battery 1311, the second secondary battery 1301a, and the third secondary battery 1301b to start the motor 1304. With such a configuration, at low temperatures, the first secondary battery 1311 may function as a cranking battery (also called a starter battery), and at high temperatures, the second secondary battery 1301a and the third secondary battery 1301b may function as cranking batteries. The motor 1304 is also called an electric motor.

[0101] Also, the power of the second secondary battery 1301a and the third secondary battery 1301b is mainly used to rotate the motor 1304, but it supplies power to 42V in-vehicle components (electric power steering 1307, defroster 1309) via the DCDC circuit 1306. Even when the rear wheels have a rear motor 1317, the second secondary battery 1301a and the third secondary battery 1301b are used to rotate the rear motor 1317.

[0102] Also, the first secondary battery 1311 not only supplies power to the heater 1308a, but may also supply power to 14V in-vehicle components (audio 1313, power window 1314, lamps 1315) via the DCDC circuit 1310.

[0103] Also, the regenerative energy generated by the rotation of the tire 1316 is sent to the motor 1304 via the gear 1305 and charged to the first secondary battery 1311 via the motor controller 1303 or the control circuit 1302 through the monitoring circuit 1321. Or it is charged to the second secondary battery 1301a via the monitoring circuit 1320a from the control circuit 1302. Or it is charged to the third secondary battery 1301b via the monitoring circuit 1320b from the control circuit 1302. In order to efficiently charge the regenerative energy, it is desirable that the second secondary battery 1301a and the third secondary battery 1301b are capable of rapid charging.

[0104] The control circuit 1302 can set the charging voltage and charging current of the second secondary battery 1301a and the third secondary battery 1301b. The control circuit 1302 can set the charging conditions according to the temperature of the secondary battery or the charging characteristics of different secondary batteries, and perform rapid charging.

[0105] Also, although not shown in the figure, when connecting to an external charger, the charger plug or the charger connection cable is electrically connected to the control circuit 1302. The power supplied from the external charger is used to charge the second secondary battery 1301a and the third secondary battery 1301b via the control circuit 1302. Also, depending on the charger, it may be provided with a control circuit and may not use the function of the control circuit 1302, but it is preferable to charge the second secondary battery 1301a and the third secondary battery 1301b via the monitoring circuits 1320a and 1320b having protection circuits for preventing overcharging. Also, the connection cable or the charger connection cable may be provided with a control circuit. The control circuit 1302 may also be called an ECU (Electronic Control Unit). The ECU is connected to a CAN (Controller Area Network) provided in the electric vehicle. CAN is one of the serial communication standards used as an in-vehicle LAN. Also, the ECU includes a microcomputer. Also, the ECU uses a CPU or a GPU.

[0106] The external charger installed on the charging stand has a 100V plug, a 200V plug, or three-phase 200V and 50kW. Also, it is possible to receive power supply from external charging facilities by a non-contact power supply method or the like and perform charging.

[0107] Since the second secondary battery 1301a can be heated by the heater 1308a heated by the first secondary battery 1311 which is a secondary battery for low temperature, it is possible to provide a control system for secondary batteries that is less affected by the ambient temperature.

[0108] This embodiment can be freely combined with other embodiments.

[0109] (Embodiment 3) In this embodiment, there is one secondary battery for low temperature as in Embodiment 1, but four secondary batteries of other types are grouped together, and a configuration example having a plurality of groups is shown in FIG. 6.

[0110] In this embodiment, as shown in the conceptual diagram of FIG. 6, a secondary battery 401 for low temperature and n (n is a multiple of 4) secondary batteries (402a, 402n) are used.

[0111] The power supply is composed of a secondary battery 401 for low temperature, a switch 403a, and a heater 450a, and is controlled by a control circuit (not shown). Specifically, the heater 450a is heated at low temperatures, and the four secondary batteries including the secondary battery 402a are heated. The switch 403a is not limited to a switch and may be a relay circuit.

[0112] One common temperature sensor 405a is provided for the four secondary batteries, and one common monitoring circuit 406a is provided. The four secondary batteries heated by the heater 450a and made available for use supply power to the heater 450b for heating the remaining secondary batteries. The heater 450b is controlled to be turned on and off by the switch 403b by the control circuit. The switch 403b may be combined with a variable resistor. The heater 450b is provided for heating the other four secondary batteries. Also, a heater using the four secondary batteries heated by the heater 450b as a power source is provided and is controlled by the switch 403c. These configurations are repeatedly arranged, and when the four secondary batteries including the last nth secondary battery 402n are heated by the heater 450n, the entire series-connected secondary batteries can be used even when the ambient temperature is low. Also, one common temperature sensor 405n is provided for the four secondary batteries including the last nth secondary battery 402n, and one common monitoring circuit 406n is provided.

[0113] The monitoring circuit 406a can also function as a cell balancer for the four secondary batteries. The cell balancer is a circuit that equalizes the voltages between a plurality of secondary batteries grouped as one group.

[0114] In Embodiment 1, individual heating is performed. However, by adopting this configuration in which a plurality of secondary batteries are divided into groups for heating, the number of temperature sensors or monitoring circuits can be reduced compared to Embodiment 1. Also, the number of heaters can be reduced compared to Embodiment 2. Further, compared to Embodiment 1, since four secondary batteries can be heated simultaneously, the time required until the preheating of the entire secondary battery is completed can be shortened.

[0115] Also, the temperature sensor and the monitoring circuit may be integrated into one IC chip.

[0116] Although not shown in FIG. 6, the control circuit is electrically connected to switches 403a, 403b, 403c, 403n for controlling the on / off of the heaters, monitoring circuits 406a, 406b, 406n, or temperature sensors 405a, 405b, 405n.

[0117] The control circuit may be configured to use a storage element having an OS transistor. Also, since the storage element using the OS transistor can be freely arranged by being stacked on a circuit using Si transistors, for example, integration can be easily performed such as a configuration in which a protection circuit is stacked on the control circuit, a configuration in which a monitoring circuit is stacked on the control circuit, or a configuration in which a temperature sensor is stacked on the control circuit. Also, since the OS transistor can be manufactured using the same manufacturing apparatus as the Si transistor, it can be manufactured at low cost.

[0118] It is preferable to use a metal oxide that functions as an oxide semiconductor in the channel formation region of the OS transistor. For example, as the metal oxide, a metal oxide such as In-M-Zn oxide (element M is one or more selected from aluminum, gallium, yttrium, copper, vanadium, beryllium, boron, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, or magnesium) may be used.

[0119] Specifically, as the metal oxide, a metal oxide with an atomic ratio of In:Ga:Zn = 1:3:4 or 1:1:0.5 may be used. Also, as the metal oxide, a metal oxide with an atomic ratio of In:Ga:Zn = 4:2:3 or 1:1:1 may be used. Further, as the metal oxide, a metal oxide with an atomic ratio of In:Ga:Zn = 1:3:4, Ga:Zn = 2:1, or Ga:Zn = 2:5 may be used. Also, as a specific example of the case where the metal oxide has a laminated structure, a laminated structure of In:Ga:Zn = 4:2:3 and In:Ga:Zn = 1:3:4, a laminated structure of Ga:Zn = 2:1 and In:Ga:Zn = 4:2:3, a laminated structure of Ga:Zn = 2:5 and In:Ga:Zn = 4:2:3, and a laminated structure of gallium oxide and In:Ga:Zn = 4:2:3 can be mentioned.

[0120] Further, the metal oxide may have crystallinity. For example, it is preferable to use CAAC-OS (c-axis aligned crystalline oxide semiconductor) described later. The oxide having the crystallinity of CAAC-OS has a dense structure with few impurities or defects (oxygen deficiency) and high crystallinity. Therefore, it is possible to suppress the extraction of oxygen from the metal oxide by the source electrode or the drain electrode. Also, even when heat treatment is performed, the extraction of oxygen from the metal oxide can be reduced, so the OS transistor is stable against a high temperature (so-called thermal budget) in the manufacturing process.

[0121] By adopting a configuration in which a memory element having an OS transistor is used in a control circuit or a protection circuit, the reference voltage can be held in the memory element by taking advantage of the fact that the leakage current (hereinafter, off-current) flowing between the source and the drain during the off state is extremely low. At this time, since the power supply of the memory element can be turned off, by using a memory element having an OS transistor, the reference voltage can be held with extremely low power consumption.

[0122] In addition, a memory element having an OS transistor can hold an analog potential. For example, the voltage of a secondary battery can be held in the memory element without converting it into a digital value using an analog-digital conversion circuit. This eliminates the need for a conversion circuit and reduces the circuit area.

[0123] In addition, in a memory element using an OS transistor, since the reference voltage can be rewritten and read by charging or discharging charges, it is possible to obtain and read the monitor voltage substantially an unlimited number of times. The memory element using an OS transistor does not involve a structural change at the atomic level like a magnetic memory or a resistive change memory, so it has excellent rewrite resistance. Also, in a memory element using an OS transistor, instability due to an increase in electron trapping centers is not recognized even in repeated rewrite operations like a flash memory.

[0124] In addition, the OS transistor has characteristics such as an extremely low off-current and good switching characteristics even in a high-temperature environment. Therefore, even in a high-temperature environment, charging or discharging control of a plurality of secondary batteries (battery packs) can be performed without malfunction.

[0125] In addition, since a memory element using an OS transistor can be freely arranged by laminating it on a circuit using an Si transistor, integration can be easily performed. Also, since the OS transistor can be manufactured using the same manufacturing equipment as an Si transistor, it can be manufactured at low cost.

[0126] In addition, an OS transistor can be a four-terminal semiconductor device by including a back gate electrode in addition to a gate electrode, a source electrode, and a drain electrode. Depending on the voltage applied to the gate electrode or the back gate electrode, an electric circuit network can be configured such that the input and output of the signal flowing between the source and the drain can be independently controlled. Therefore, circuit design can be performed with the same concept as that for an LSI. In addition, the OS transistor has better electrical characteristics than an Si transistor in a high-temperature environment. Specifically, since the ratio of the on-current to the off-current is large even at a high temperature of 100°C or higher and 200°C or lower, preferably 125°C or higher and 150°C or lower, a good switching operation can be performed.

[0127] This embodiment can be freely combined with other embodiments.

[0128] (Embodiment 4) In this embodiment, an example of a cylindrical secondary battery that can be used for the secondary batteries 102a, 102b, 102c, 102d, and 102e shown in Embodiment 1 will be described with reference to FIG. 7.

[0129] As shown in FIG. 7A, the cylindrical secondary battery 600 has a positive electrode cap (battery lid) 601 on the upper surface and a battery can (outer can) 602 on the side surface and the bottom surface. The positive electrode cap and the battery can (outer can) 602 are insulated by a gasket (insulating packing) 610.

[0130] FIG. 7B is a diagram schematically showing a cross section of a cylindrical secondary battery. Inside a hollow cylindrical battery can 602, a battery element is provided in which a strip-shaped positive electrode 604 and a negative electrode 606 are wound with a separator 605 interposed therebetween. 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. For the battery can 602, metals such as nickel, aluminum, titanium, etc. that are corrosion-resistant to the solvent, or alloys thereof or alloys of these with other metals (for example, stainless steel, etc.) can be used. Further, in order to prevent corrosion by the solvent, it is preferable to coat with nickel or aluminum, etc. Inside the battery can 602, the battery element in which the positive electrode, negative electrode, and separator are wound is sandwiched by a pair of opposing insulating plates 608 and 609. Further, a non-aqueous electrolyte (not shown) is injected into the interior of the battery can 602 in which the battery element is provided. As the non-aqueous electrolyte, the same one as that used for a coin-type secondary battery can be used.

[0131] Since the positive and negative electrodes used in a cylindrical storage battery are wound, it is preferable to form the active material on both sides of the current collector. A positive electrode terminal (positive current collector lead) 603 is connected to the positive electrode 604, and a negative electrode terminal (negative current collector lead) 607 is connected to the negative electrode 606. Both the positive electrode terminal 603 and the negative electrode terminal 607 can use a metal material of aluminum. The positive electrode terminal 603 is resistance-welded to the safety valve mechanism 612, and the negative electrode terminal 607 is resistance-welded to the bottom of the battery can 602, respectively. The safety valve mechanism 612 is electrically connected to the positive electrode cap 601 via a PTC (Positive Temperature Coefficient) element 611. The safety valve mechanism 612 disconnects the electrical connection between the positive electrode cap 601 and the positive electrode 604 when the internal pressure of the battery rises beyond a predetermined threshold value. Further, the PTC element 611 is a thermal sensing resistance element whose resistance increases when the temperature rises, and restricts the current amount due to the increase in resistance to prevent abnormal heat generation. For the PTC element, barium titanate (BaTiO3)-based semiconductor ceramics, etc. can be used.

[0132] Further, as shown in FIG. 7C, a module 615 may be configured by sandwiching a plurality of secondary batteries 600 between a conductive plate 613 and a conductive plate 614. The plurality of secondary batteries 600 may be connected in parallel, in series, or in parallel first and then in series. By configuring the module 615 having the plurality of secondary batteries 600, a large amount of power can be extracted.

[0133] FIG. 7D is a top view of the module 615. The conductive plate 613 is shown by a dotted line for clarity. As shown in FIG. 7D, the module 615 may have a conductive wire 616 that electrically connects the plurality of secondary batteries 600. A conductive plate can be superimposed and provided on the conductive wire 616. Further, a heater 617 may be provided between the plurality of secondary batteries 600. In FIG. 7D, one of the heaters 617 is configured to heat the secondary batteries 600 grouped in 24 units each. When mounted on a vehicle, a plurality of groups are provided. Therefore, a configuration is adopted in which a plurality of heaters 617 are provided, and each has a control circuit capable of heating. When the secondary battery 600 is cooled by the external environment to below the lower limit of the operating temperature, it can be heated by the heater 617 powered by the low-temperature secondary battery. Further, by providing the low-temperature secondary battery, the performance of the module 615 is less affected by the outside air temperature. The heat medium of the heater 617 preferably has insulation and non-combustibility.

[0134] By using the secondary battery temperature control system described in the previous embodiment, a low-temperature secondary battery can be provided, and the module 615 can be made less affected by the environmental temperature.

[0135] [Structural Example of Secondary Battery] A structural example of the secondary battery will be described with reference to FIGS. 8 and 9.

[0136] The secondary battery 913 shown in FIG. 8A has a wound body 950 in which a terminal 951 and a terminal 952 are provided inside a housing 930. The terminal 952 is in contact with the housing 930, and the terminal 951 is not in contact with the housing 930 by using an insulating material. In FIG. 8A, for the sake of convenience, the housing 930 is shown separately, but actually, the wound body 950 is covered by the housing 930, and the terminals 951 and 952 extend outside the housing 930. As the housing 930, a metal material (for example, aluminum) or a resin material can be used.

[0137] In addition, as shown in FIG. 8B, the housing 930 shown in FIG. 8A may be formed of a plurality of materials. For example, the secondary battery 913 shown in FIG. 8B has a housing 930a and a housing 930b bonded together, and a wound body 950 is provided in a region surrounded by the housing 930a and the housing 930b.

[0138] As the housing 930a, an insulating material such as an organic resin can be used. In particular, by using a material such as an organic resin on the surface where the antenna is formed, shielding of the electric field by the secondary battery 913 can be suppressed. If the shielding of the electric field by the housing 930a is small, an antenna may be provided inside the housing 930a. As the housing 930b, for example, a metal material can be used.

[0139] Furthermore, the structure of the wound body 950 is shown in FIG. 8C. The wound body 950 has a negative electrode 931, a positive electrode 932, and a separator 933. The wound body 950 is a wound body in which the negative electrode 931 and the positive electrode 932 overlap and are laminated with the separator 933 interposed therebetween, and the laminated sheet is wound. In addition, a plurality of laminations of the negative electrode 931, the positive electrode 932, and the separator 933 may be further stacked.

[0140] Also, a secondary battery 913 having a wound body 950a as shown in FIG. 9 may be used. The wound body 950a shown in FIG. 9A 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.

[0141] The separator 933 has a width wider 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. Also, from the viewpoint of safety, it is preferable that the width of the negative electrode active material layer 931a is wider than that of the positive electrode active material layer 932a. Further, the wound body 950a having such a shape is preferable in terms of safety and productivity.

[0142] As shown in FIG. 9B, the negative electrode 931 is electrically connected to the terminal 951. The terminal 951 is electrically connected to the terminal 911a. Also, the positive electrode 932 is electrically connected to the terminal 952. The terminal 952 is electrically connected to the terminal 911b. As shown in FIG. 9B, two wound bodies 950a are housed in one housing 930.

[0143] As shown in FIG. 9C, the wound body 950a is covered by the housing 930 to form the secondary battery 913. It is preferable to provide a safety valve, an overcurrent protection element, etc. in the housing 930. The safety valve is a valve that opens when the inside of the housing 930 reaches a predetermined internal pressure in order to prevent battery rupture.

[0144] As shown in FIG. 9B, the secondary battery 913 may have a plurality of wound bodies 950a. By using a plurality of wound bodies 950a, a secondary battery 913 with a larger charge / discharge capacity can be obtained. For other elements of the secondary battery 913 shown in FIGS. 9A and 9B, the description of the secondary battery 913 shown in FIGS. 8A to 8C can be referred to.

[0145] <Laminated secondary battery> Next, an example of a laminated secondary battery is shown in FIGS. 10A and 10B as an example of an external view. FIGS. 10A and 10B have a positive electrode 503, a negative electrode 506, a separator 507, an exterior body 509, a positive electrode lead electrode 510, and a negative electrode lead electrode 511.

[0146] FIG. 11A shows the external views of the positive electrode 503 and the negative electrode 506. The positive electrode 503 has a positive electrode current collector 501, and the positive electrode active material layer 502 is formed on the surface of the positive electrode current collector 501. Further, the positive electrode 503 has a region where the positive electrode current collector 501 is partially exposed (hereinafter referred to as a tab region). The negative electrode 506 has a negative electrode current collector 504, and the negative electrode active material layer 505 is formed on the surface of the negative electrode current collector 504. Further, the negative electrode 506 has a region where the negative electrode current collector 504 is partially exposed, that is, a tab region. The area or shape of the tab regions of the positive electrode and the negative electrode is not limited to the example shown in FIG. 11A.

[0147] <Method for manufacturing a laminated secondary battery> Here, an example of a method for manufacturing a laminated secondary battery whose external view is shown in FIG. 10A will be described with reference to FIGS. 11B and 11C.

[0148] First, the negative electrode 506, the separator 507, and the positive electrode 503 are laminated. FIG. 11B shows the laminated negative electrode 506, separator 507, and positive electrode 503. Here, an example in which five negative electrodes and four positive electrodes are used is shown. It can also be called a laminate composed of a negative electrode, a separator, and a positive electrode. Next, the tab regions of the positive electrode 503 are joined to each other, and the positive electrode lead electrode 510 is joined to the tab region of the outermost positive electrode. For the joining, for example, ultrasonic welding or the like may be used. Similarly, the tab regions of the negative electrode 506 are joined to each other, and the negative electrode lead electrode 511 is joined to the tab region of the outermost negative electrode.

[0149] Next, the negative electrode 506, the separator 507, and the positive electrode 503 are arranged on the exterior body 509.

[0150] [Negative electrode] The negative electrode has a negative electrode active material layer and a negative electrode current collector. Further, the negative electrode active material layer may have a conductive auxiliary agent and a binder.

[0151] [Negative electrode active material] As the negative electrode active material, for example, an alloy-based material or a carbon-based material can be used.

[0152] As the negative electrode active material, an element capable of performing a charge-discharge reaction by an alloying / dealloying reaction with lithium can be used. For example, a material containing at least one of silicon, tin, gallium, aluminum, germanium, lead, antimony, bismuth, silver, zinc, cadmium, indium, etc. can be used. Such elements have a larger capacity compared to carbon, and in particular, silicon has a high theoretical capacity of 4200 mAh / g. Therefore, it is preferable to use silicon as the negative electrode active material. Also, compounds containing these elements may be used. For example, there are SiO, Mg2Si, Mg2Ge, SnO, SnO2, Mg2Sn, SnS2, V2Sn3, FeSn2, CoSn2, Ni3Sn2, Cu6Sn5, Ag3Sn, Ag3Sb, Ni2MnSb, CeSb3, LaSn3, La3Co2Sn7, CoSb3, InSb, SbSn, etc. Here, an element capable of performing a charge-discharge reaction by an alloying / dealloying reaction with lithium, and a compound containing the element, etc. may be referred to as an alloy-based material.

[0153] In this specification, etc., SiO refers to, for example, silicon monoxide. Alternatively, SiO can also be represented as SiO x where x preferably has a value of 1 or near 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.

[0154] As the carbon-based material, graphite, graphitizable carbon (soft carbon), non-graphitizable carbon (hard carbon), carbon nanotubes, graphene, carbon black, etc. may be used.

[0155] Examples of graphite include artificial graphite or natural graphite. Examples of artificial graphite include mesocarbon microbeads (MCMB), coke-based artificial graphite, pitch-based artificial graphite, etc. Here, spherical graphite having a spherical shape can be used as the artificial graphite. For example, MCMB may have a spherical shape, which is preferable. Also, it is relatively easy to reduce the surface area of MCMB, which may be preferable. Examples of natural graphite include flaky graphite, spheroidized natural graphite, etc.

[0156] Graphite exhibits a potential as low as that of metallic lithium when lithium ions are inserted into it (when forming a lithium-graphite intercalation compound) (0.05 V or more and 0.3 V or less vs. Li / Li + ). As a result, lithium-ion secondary batteries can exhibit a high operating voltage. Furthermore, graphite has advantages such as a relatively high capacity per unit volume, relatively small volume expansion, low cost, and high safety compared to metallic lithium, so it is preferable.

[0157] In addition, as the negative electrode active material, oxides such as titanium dioxide (TiO2), lithium titanate (Li4Ti5O 12 ), lithium-graphite intercalation compound (Li x C6), niobium pentoxide (Nb2O5), tungsten oxide (WO2), molybdenum oxide (MoO2) can be used.

[0158] In addition, as the negative electrode active material, Li 3-x M x N (M = Co, Ni, Cu) having an Li3N type structure, which is a complex nitride of lithium and a transition metal, can be used. For example, Li 2.6 Co 0.4 N3 exhibits a large charge-discharge capacity (900 mAh / g, 1890 mAh / cm 3 ) and is preferable.

[0159] When using a complex nitride of lithium and a transition metal, since the negative electrode active material contains lithium ions, it can be preferably combined with materials such as V2O5 and Cr3O8 that do not contain lithium ions as the positive electrode active material. Even when using a material containing lithium ions as the positive electrode active material, by previously desorbing the lithium ions contained in the positive electrode active material, a complex nitride of lithium and a transition metal can be used as the negative electrode active material.

[0160] In addition, materials in which a conversion reaction occurs can also be used as the negative electrode active material. For example, transition metal oxides that do not form an alloy with lithium, such as cobalt oxide (CoO), nickel oxide (NiO), and iron oxide (FeO), may be used as the negative electrode active material. Materials in which a conversion reaction occurs further include oxides such as Fe2O3, CuO, Cu2O, RuO2, and Cr2O3, CoS 0.89 The conversion reaction also occurs with sulfides such as NiS, CuS, nitrides such as Zn3N2, Cu3N, and Ge3N4, phosphides such as NiP2, FeP2, and CoP3, and fluorides such as FeF3 and BiF3.

[0161] As the conductive assistant and binder that the negative electrode active material layer can have, the same materials as those that the positive electrode active material layer can have can be used.

[0162] [Negative electrode current collector] For the negative electrode current collector, the same materials as those for the positive electrode current collector can be used. It is preferable to use a material that does not alloy with carrier ions such as lithium for the negative electrode current collector.

[0163] [Separator] A separator is disposed between the positive electrode and the negative electrode. As the separator, for example, those formed of fibers having cellulose such as paper, non-woven fabrics, glass fibers, ceramics, or synthetic fibers using nylon (polyamide), vinylon (polyvinyl alcohol-based fiber), polyester, acrylic, polyolefin, polyurethane, etc. can be used. The separator is preferably processed into a bag shape and disposed so as to wrap either the positive electrode or the negative electrode.

[0164] The separator may have a multilayer structure. For example, an organic material film such as polypropylene or polyethylene can be coated with a ceramic-based material, a fluorine-based material, a polyamide-based material, or a mixture thereof. As the ceramic-based material, for example, aluminum oxide particles, silicon oxide particles, etc. can be used. As the fluorine-based material, for example, PVDF, polytetrafluoroethylene, etc. can be used. As the polyamide-based material, for example, nylon, aramid (meta-aramid, para-aramid), etc. can be used.

[0165] Coating with a ceramic-based material improves oxidation resistance, thus suppressing the deterioration of the separator during high-voltage charge and discharge and improving the reliability of the secondary battery. Also, coating with a fluorine-based material makes it easier for the separator and the electrode to adhere, improving the output characteristics. Coating with a polyamide-based material, especially aramid, improves heat resistance, thus improving the safety of the secondary battery.

[0166] For example, both sides of a polypropylene film can be coated with a mixed material of aluminum oxide and aramid. Also, the side of the polypropylene film in contact with the positive electrode can be coated with a mixed material of aluminum oxide and aramid, and the side in contact with the negative electrode can be coated with a fluorine-based material.

[0167] Using a separator with a multilayer structure can maintain the safety of the secondary battery even when the overall thickness of the separator is thin, so the capacity per unit volume of the secondary battery can be increased.

[0168] [Positive electrode] The positive electrode has a positive electrode active material layer and a positive electrode current collector. Also, the positive electrode active material layer may have a conductive assistant and a binder.

[0169] <Positive electrode active material> As the positive electrode active material, it is preferable to have a metal that serves as a carrier ion (hereinafter referred to as element A). As element A, for example, alkali metals such as lithium, sodium, and potassium, and Group 2 elements such as calcium, beryllium, and magnesium can be used.

[0170] In the positive electrode active material, carrier ions are desorbed from the positive electrode active material during charging. If there is a large amount of desorption of element A, there are many ions that contribute to the capacity of the secondary battery, and the capacity increases. On the other hand, if there is a large amount of desorption of element A, the crystal structure of the compound contained in the positive electrode active material is likely to collapse. The collapse of the crystal structure of the positive electrode active material may lead to a decrease in the discharge capacity during charge-discharge cycles. When the positive electrode active material has element X, the collapse of the crystal structure during the desorption of carrier ions during charging of the secondary battery may be suppressed. Element X is, for example, partially substituted at the position of element A. As element X, elements such as magnesium, calcium, zirconium, lanthanum, and barium can be used. Also, for example, elements such as copper, potassium, sodium, and zinc can be used as element X. Further, two or more of the above-mentioned elements may be used in combination as element X.

[0171] In addition, the positive electrode active material preferably has a halogen in addition to element X. It is preferable to have a halogen such as fluorine or chlorine. When the positive electrode active material has the halogen, the substitution of element X at the position of element A may be promoted.

[0172] When the positive electrode active material has element X, or when it has a halogen in addition to element X, the electrical conductivity on the surface of the positive electrode active material may be suppressed.

[0173] Further, the positive electrode active material has a metal (hereinafter, element M) whose valence changes due to charging and discharging of the secondary battery. Element M is, for example, a transition metal. The positive electrode active material has, for example, one or more of cobalt, nickel, and manganese as element M, and particularly has cobalt. Further, at the position of element M, an element such as aluminum that does not change in valence and can have the same valence as element M, more specifically, a trivalent typical element, may be provided. The aforementioned element X may be substituted, for example, at the position of element M. Further, when the positive electrode active material is an oxide, element X may be substituted at the position of oxygen.

[0174] As the positive electrode active material, it is preferable to use, for example, a lithium composite oxide having a layered rock salt-type crystal structure. More specifically, for example, as the lithium composite oxide having a layered rock salt-type crystal structure, lithium cobaltate, lithium nickelate, a lithium composite oxide having nickel, manganese, and cobalt, a lithium composite oxide having nickel, cobalt, and aluminum, etc. can be used. Further, these positive electrode active materials are preferably represented by the space group R-3m.

[0175] In the positive electrode active material having a layered rock salt-type crystal structure, when the depth of charge is increased, the crystal structure may collapse. Here, the collapse of the crystal structure is, for example, the shift of layers. When the collapse of the crystal structure is irreversible, the capacity of the secondary battery may decrease with repeated charging and discharging.

[0176] When the positive electrode active material has element X, for example, even when the depth of charge becomes deep, the above-described layer shift is suppressed. By suppressing the shift, the volume change during charge and discharge can be reduced. Therefore, the positive electrode active material can realize excellent cycle characteristics. Further, the positive electrode active material can have a stable crystal structure in a charged state at a high voltage. Therefore, when the positive electrode active material maintains a charged state at a high voltage, a short circuit may be less likely to occur. In such a case, since the safety is further improved, it is preferable.

[0177] In the positive electrode active material, the change in crystal structure and the difference in volume per the same number of transition metal atoms in the fully discharged state and the state charged at a high voltage are small.

[0178] The positive electrode active material may be represented by the chemical formula AM y O Z (y > 0, z > 0). For example, lithium cobaltate may be represented by LiCoO2. Also, for example, lithium nickelate may be represented by LiNiO2.

[0179] In the positive electrode active material having element X, when the depth of charge is 0.8 or more, it is represented by the space group R-3m and is not a spinel-type crystal structure, but ions such as element M (for example, cobalt) and element X (for example, magnesium) occupy the oxygen six-coordination positions, and the arrangement of cations may have symmetry similar to that of the spinel type. This structure is referred to as a pseudo-spinel-type crystal structure in this specification and the like. Note that in the pseudo-spinel-type crystal structure, light elements of lithium may occupy the oxygen four-coordination positions, and in this case as well, the arrangement of ions has symmetry similar to that of the spinel type.

[0180] Due to the desorption of carrier ions accompanying charging, the structure of the positive electrode active material becomes unstable. It can be said that the pseudo-spinel-type crystal structure is a structure that can maintain high stability even though carrier ions have desorbed.

[0181] Also, it can be said that the pseudo-spinel-type crystal structure is a crystal structure similar to the CdCl2-type crystal structure although it has Li randomly between layers. This crystal structure similar to the CdCl2 type is close to the crystal structure when lithium nickelate is charged to a depth of charge of 0.94 (Li 0.06 NiO2), but it is known that pure lithium cobaltate or a layered rock salt-type positive electrode active material containing a large amount of cobalt usually does not take this crystal structure.

[0182] In layered rock salt-type crystals and rock salt-type crystals, the anions adopt a cubic close-packed structure (face-centered cubic lattice structure). It is presumed that in pseudo-spinel-type crystals as well, the anions adopt a cubic close-packed structure. When these come into contact, there exists a crystal plane where the orientations of the cubic close-packed structures composed of anions are aligned. However, since the space groups of layered rock salt-type crystals and pseudo-spinel-type crystals are R-3m, which is different from the space groups of rock salt-type crystals, Fm-3m (the space group of a general rock salt-type crystal) and Fd-3m (the space group of a rock salt-type crystal with the simplest symmetry), the Miller indices of the crystal planes satisfying the above conditions are different between layered rock salt-type crystals and pseudo-spinel-type crystals and rock salt-type crystals. In this specification, in the case of layered rock salt-type crystals, pseudo-spinel-type crystals, and rock salt-type crystals, when the orientations of the cubic close-packed structures composed of anions are aligned, it may be said that the crystal orientations are approximately the same.

[0183] The crystal structure of the pseudo-spinel type can be represented by the coordinates of cobalt and oxygen in the unit cell as Co(0, 0, 0.5), O(0, 0, x), where 0.20 ≤ x ≤ 0.25.

[0184] In the positive electrode active material, the difference between the volume of the unit cell at a charge depth of 0 and the volume per unit cell of the pseudo-spinel type crystal structure at a charge depth of 0.82 is preferably 2.5% or less, and more preferably 2.2% or less.

[0185] In the pseudo-spinel type crystal structure, diffraction peaks appear at 2θ = 19.30 ± 0.20° (19.10° or more and 19.50° or less), and 2θ = 45.55 ± 0.10° (45.45° or more and 45.65° or less). More specifically, sharp diffraction peaks appear at 2θ = 19.30 ± 0.10° (19.20° or more and 19.40° or less), and 2θ = 45.55 ± 0.05° (45.50° or more and 45.60° or less).

[0186] The positive electrode active material has a pseudo-spinel type crystal structure when charged at a high voltage, but not all of the particles need to have a pseudo-spinel type crystal structure. It may contain other crystal structures or a part thereof may be amorphous. However, when Rietveld analysis is performed on the XRD pattern, the pseudo-spinel type crystal structure is preferably 50 wt% or more, more preferably 60 wt% or more, and even more preferably 66 wt% or more. If the pseudo-spinel type crystal structure is 50 wt% or more, more preferably 60 wt% or more, and even more preferably 66 wt% or more, a positive electrode active material with excellent cycle characteristics can be obtained.

[0187] The number of atoms of element X is preferably 0.001 times or more and 0.1 times or less, more preferably more than 0.01 and less than 0.04, and even more preferably about 0.02, the number of atoms of element M. The concentration of element X shown here may be, for example, a value obtained by performing elemental analysis of the entire particles of the positive electrode active material using ICP-MS or the like, or may be based on the value of the raw material formulation in the process of producing the positive electrode active material.

[0188] When the element M has cobalt and nickel, the ratio Ni / (Co + Ni) of the number of atoms of nickel (Ni) to the sum of the number of atoms of cobalt and nickel (Co + Ni) is preferably less than 0.1, and more preferably 0.075 or less.

[0189] The positive electrode active material is not limited to the materials listed above.

[0190] As the positive electrode active material, for example, a composite oxide having a spinel type crystal structure can be used. Further, as the positive electrode active material, for example, a polyanion-based material can be used. Examples of the polyanion-based material include a material having an olivine type crystal structure, a NASICON type material, and the like. Further, as the positive electrode active material, for example, a material containing sulfur can be used.

[0191] As a material having a spinel-type crystal structure, for example, a composite oxide represented by LiM2O4 can be used. It is preferable that the element M has Mn. For example, LiMn2O4 can be used. Further, by having Ni in addition to Mn as the element M, the discharge voltage of the secondary battery may be improved and the energy density may be improved, which is preferable. Further, a small amount of lithium nickelate (LiNiO2 or LiNi 1-x M x O2 (M = Co, Al, etc.)) is preferably mixed to improve the characteristics of the secondary battery.

[0192] As a polyanion-based material, for example, a composite oxide having oxygen, metal A, metal M, and element Z can be used. Metal A is one or more of Li, Na, and Mg, metal M is one or more of Fe, Mn, Co, Ni, Ti, V, and Nb, and element Z is one or more of S, P, Mo, W, As, and Si.

[0193] As a material having an olivine-type crystal structure, for example, a composite material (general formula LiMPO4 (M is one or more of Fe(II), Mn(II), Co(II), and Ni(II))) can be used. Representative examples of the general formula LiMPO4 include LiFePO4, LiNiPO4, LiCoPO4, LiMnPO4, LiFe a Ni b PO4, LiFe a Co b PO4, LiFe a Mn b PO4, LiNi a Co b PO4, LiNi a Mn b PO4 (a + b is 1 or less, 0 < a < 1, 0 < b < 1), LiFe c Ni d Co e PO4, LiFe c Ni d Mn e PO4, LiNi c Co d Mn ePO4 (where c + d + e ≤ 1, 0 < c < 1, 0 < d < 1, 0 < e < 1), LiFe f Ni g Co h Mn i PO4 (where f + g + h + i ≤ 1, 0 < f < 1, 0 < g < 1, 0 < h < 1, 0 < i < 1), etc., can be used as the lithium compound.

[0194] Also, composite materials such as the general formula Li (2-j) MSiO4 (M is one or more of Fe(II), Mn(II), Co(II), Ni(II), 0 ≤ j ≤ 2), etc., can be used. For the general formula Li (2-j) Typical examples of MSiO4 include Li (2-j) FeSiO4, Li (2-j) NiSiO4, Li (2-j) CoSiO4, Li (2-j) MnSiO4, Li (2-j) Fe k Ni l SiO4, Li (2-j) Fe k Co l SiO4, Li (2-j) Fe k Mn l SiO4, Li (2-j) Ni k Co l SiO4, Li (2-j) Ni k Mn l SiO4 (where k + l ≤ 1, 0 < k < 1, 0 < l < 1), Li (2-j) Fe m Ni n Co q SiO4, Li (2-j) Fe m Ni n Mn q SiO4, Li (2-j) Ni m Co n Mn q SiO4 (where m + n + q ≤ 1, 0 < m < 1, 0 < n < 1, 0 < q < 1), Li (2-j) Fe r Ni s Co t Mn uLithium compounds such as SiO4 (where r + s + t + u ≤ 1, 0 < r < 1, 0 < s < 1, 0 < t < 1, 0 < u < 1) can be used as materials.

[0195] Also, A x NASICON-type compounds represented by the general formula M2(XO4)3 (A = Li, Na, Mg, M = Fe, Mn, Ti, V, Nb, X = S, P, Mo, W, As, Si) can be used. Examples of NASICON-type compounds include Fe2(MnO4)3, Fe2(SO4)3, Li3Fe2(PO4)3, etc. Also, as the positive electrode active material, compounds represented by the general formula Li2MPO4F, Li2MP2O7, Li5MO4 (M = Fe, Mn) can be used.

[0196] Also, as the positive electrode active material, perovskite-type fluorides such as NaFeF3, FeF3, metal chalcogenides (sulfides, selenides, tellurides) such as TiS2, MoS2, oxides having an inverse spinel-type crystal structure such as LiMVO4, vanadium oxide-based (V2O5, V6O 13 , LiV3O8, etc.), manganese oxides, organic sulfur compounds and other materials may be used.

[0197] Also, as the positive electrode active material, borate-based materials represented by the general formula LiMBO3 (M is Fe(II), Mn(II), Co(II)) may be used.

[0198] Examples of materials containing sodium include NaFeO2 or Na 2 / 3 [Fe 1 / 2 Mn 1 / 2 O2, Na 2 / 3 [Ni 1 / 3 Mn 2 / 3 O2, Na2Fe2(SO4)3, Na3V2(PO4)3, Na2FePO4F, NaVPO4F, NaMPO4 (M is Fe(II), Mn(II), Co(II), Ni(II)), Na2FePO4F, Na4Co3(PO4)2P2O7, and sodium-containing oxides may be used as the positive electrode active material.

[0199] Further, a lithium-containing metal sulfide may be used as the positive electrode active material. For example, Li2TiS3, Li3NbS4, etc. may be mentioned.

[0200] As the positive electrode active material used in this embodiment, two or more of the materials listed above may be mixed and used.

[0201] Next, as shown in FIG. 11C, the exterior body 509 is bent at the portion indicated by the broken line. Then, the outer peripheral portion of the exterior body 509 is joined. For joining, for example, thermocompression bonding or the like may be used. At this time, a region (hereinafter referred to as an inlet) that is not joined to a part (or one side) of the exterior body 509 is provided so that an electrolytic solution (also referred to as an electrolyte) 508 can be put in later.

[0202] Next, the electrolytic solution 508 (not shown) is introduced into the interior of the exterior body 509 from the inlet provided in the exterior body 509. The introduction of the electrolytic solution 508 is preferably performed under a reduced-pressure atmosphere or an inert atmosphere. And finally, the inlet is joined. In this way, the laminated secondary battery 500 can be manufactured.

[0203] This embodiment can be freely combined with other embodiments.

[0204] (Embodiment 5) In this embodiment, an example of manufacturing a semi-solid battery as the low-temperature secondary battery shown in Embodiment 1 is shown.

[0205] FIG. 12A is a schematic cross-sectional view of a secondary battery 1000 according to an aspect of the present invention. The secondary battery 1000 has a positive electrode 1006, an electrolyte layer 1003, and a negative electrode 1007. The positive electrode 1006 has a positive electrode current collector 1001 and a positive electrode active material layer 1002. The negative electrode 1007 has a negative electrode current collector 1005 and a negative electrode active material layer 1004.

[0206] Figure 12B is a schematic cross-sectional view of the positive electrode 1006. The positive electrode active material layer 1002 of the positive electrode 1006 includes a positive electrode active material 1011, an electrolyte 1010, and a conductive material (also referred to as a conductive aid). The electrolyte 1010 includes a lithium ion conductive polymer and a lithium salt. Further, it is preferable that the positive electrode active material layer 1002 does not have a binder.

[0207] Figure 12C is a schematic cross-sectional view of the electrolyte layer 1003. The electrolyte layer 1003 includes an electrolyte 1010 including a lithium ion conductive polymer and a lithium salt.

[0208] In this specification and the like, the lithium ion conductive polymer is a polymer having conductivity for cations such as lithium. More specifically, it is a high molecular compound having a polar group capable of coordinating cations. As the polar group, it is preferable to have an ether group, an ester group, a nitrile group, a carbonyl group, a siloxane, or the like.

[0209] As the lithium ion conductive polymer, for example, polyethylene oxide (PEO), a derivative having polyethylene oxide as the main chain, polypropylene oxide, polyacrylate, polymethacrylate, polysiloxane, polyphosphazene, or the like can be used.

[0210] The lithium ion conductive polymer may be branched or crosslinked. It may also be a copolymer. The molecular weight is preferably, for example, 10,000 or more, and more preferably 100,000 or more.

[0211] Lithium ion conductive polymers allow lithium ions to move while changing the polar groups that interact through the segmental motion (also called segment motion) of the polymer chains. For example, in the case of PEO, lithium ions move while changing the oxygen that interacts through the segmental motion of the ether chains. When the temperature is close to or higher than the melting point or softening point of the lithium ion conductive polymer, the crystalline regions dissolve and the amorphous regions increase, and the motion of the ether chains becomes active, so the ionic conductivity increases. Therefore, when using PEO as a lithium ion conductive polymer, it is preferable to perform charge and discharge at 60 °C or higher.

[0212] According to the Shannon ionic radius (Shannon et al., Acta A 32 (1976) 751.), the radius of monovalent lithium ions is 0.590 Å in the case of 4 coordination, 0.76 Å in the case of 6 coordination, and 0.92 Å in the case of 8 coordination. Also, the radius of divalent oxygen ions is 1.35 Å in the case of 2 coordination, 1.36 Å in the case of 3 coordination, 1.38 Å in the case of 4 coordination, 1.40 Å in the case of 6 coordination, and 1.42 Å in the case of 8 coordination. The distance between the polar groups of adjacent lithium ion conductive polymer chains is preferably greater than or equal to the distance at which lithium ions and the anions of the polar groups can stably exist while maintaining the ionic radii as described above. And it is preferably a distance at which sufficient interaction occurs between the lithium ions and the polar groups. However, as described above, due to the occurrence of segmental motion, it is not always necessary to maintain a constant distance. It is sufficient if it is an appropriate distance when the lithium ions pass through.

[0213] As the lithium salt, for example, a compound having at least one or more of phosphorus, fluorine, nitrogen, sulfur, oxygen, chlorine, arsenic, boron, aluminum, bromine, iodine together with lithium can be used. For example, LiPF6, LiN(FSO2)2 (lithium bis(fluorosulfonyl)imide, LiFSI), LiClO4, LiAsF6, LiBF4, LiAlCl4, LiSCN, LiBr, LiI, Li2SO4, Li2B 10 Cl 10 、Li2B 12 Cl 12One or more lithium salts such as LiCF3SO3, LiC4F9SO3, LiC(CF3SO2)3, LiC(C2F5SO2)3, LiN(CF3SO2)2, LiN(C4F9SO2)(CF3SO2), LiN(C2F5SO2)2, lithium bis(oxalate) borate (LiBOB) can be used alone or in any combination and ratio of two or more of these.

[0214] In particular, when using LiFSI, the low-temperature characteristics are good, which is preferable. Also, LiFSI and LiTFSA are less likely to react with water compared to LiPF6 etc. Therefore, it becomes easier to control the dew point when fabricating electrodes and electrolyte layers using LiFSI. For example, it can be handled not only in an inert atmosphere with as little moisture excluded as possible and a dry room with controlled dew point, but also in a normal atmospheric atmosphere. Therefore, the productivity is improved, which is preferable. Also, it is particularly preferable to use a highly dissociable and plasticizing-effect Li salt such as LiFSI or LiTFSA when using lithium conduction utilizing the segmental motion of the ether chain because it can be used in a wide temperature range.

[0215] Also, in this specification etc., the binder refers to a polymer compound that is mixed only for binding active materials, conductive materials, etc. onto a current collector. For example, materials such as polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), styrene-isoprene-styrene rubber, butadiene rubber, ethylene-propylene-diene copolymer rubber materials, fluororubber, polystyrene, polyvinyl chloride, polytetrafluoroethylene, polyethylene, polypropylene, polyisobutylene, ethylene propylene diene polymer.

[0216] Since the lithium ion conductive polymer is a high molecular compound, it can be well mixed and used in the positive electrode active material layer 1002 to bind the positive electrode active material 1011 and the conductive material onto the positive electrode current collector 1001. Therefore, the positive electrode 1006 can be manufactured without using a binder. A binder is a material that does not contribute to the charge and discharge reaction. Therefore, the less binder there is, the more materials that contribute to the charge and discharge of the active material, electrolyte, etc. can be increased. Therefore, a secondary battery 1000 with improved discharge capacity, rate characteristics, cycle characteristics, etc. can be obtained.

[0217] In addition, since both the positive electrode active material layer 1002 and the electrolyte layer 1003 have the electrolyte 1010, the contact at the interface between the positive electrode active material layer 1002 and the electrolyte layer 1003 becomes good. Therefore, a secondary battery 1000 with improved rate characteristics, discharge capacity, cycle characteristics, etc. can be obtained.

[0218] Since there is no or very little organic solvent, a secondary battery that is difficult to catch fire or ignite can be obtained, and the safety is improved, which is preferable. Also, if the electrolyte layer 1003 uses the electrolyte 1010 with no or very little organic solvent, it has sufficient strength even without a separator and can electrically insulate the positive electrode and the negative electrode. Since a separator is not required, a highly productive secondary battery can be obtained. If the electrolyte 1010 has the inorganic filler 1015, the strength is further increased, and a safer secondary battery can be obtained.

[0219] In order to make the electrolyte 1010 have no or very little organic solvent, it is preferable that the electrolyte 1010 is sufficiently dried. In this specification, etc., when the weight change of the electrolyte 1010 when dried under reduced pressure at 90°C for 1 hour is within 5%, it is considered to be sufficiently dried.

[0220] The electrolyte layer 1003 may also contain additives such as vinylene carbonate, propane sultone (PS), tert-butylbenzene (TBB), fluoroethylene carbonate (FEC), lithium bis(oxalate) borate (LiBOB), and dinitrile compounds such as succinonitrile and adiponitrile. The concentration of the additive material may be, for example, 0.1 wt% or more and 5 wt% or less with respect to the entire electrolyte layer 1003.

[0221] For the identification of materials such as lithium ion conductive polymers, lithium salts, binders, and additives contained in the secondary battery, for example, nuclear magnetic resonance (NMR) can be used. Also, the analysis results of Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), time-of-flight secondary ion mass spectrometry (TOF-SIMS), gas chromatography mass spectrometry (GC / MS), pyrolysis gas chromatography mass spectrometry (Py-GC / MS), liquid chromatography mass spectrometry (LC / MS), etc. may be used as materials for judgment. It is preferable to suspend the positive electrode active material layer 1002 in a solvent, separate the positive electrode active material 1011 and other materials, and then subject them to analysis such as NMR.

[0222] This embodiment is not limited to the cross-section of the positive electrode in FIG. 12B. For example, as an example different from FIG. 12B, cross-sectional views of the positive electrode are shown in FIGS. 13A, 13B, 13C, and 13D.

[0223] As the positive electrode of the secondary battery, a binder (resin) is mixed to fix the current collector 550 of the metal foil and the active material 551. The binder is also called a binding material. The binder is a polymer material. If a large amount of binder is included, the proportion of the active material in the positive electrode decreases, and the discharge capacity of the secondary battery becomes small. Therefore, the amount of the binder is mixed to the minimum. In FIG. 10A, the regions not filled with the active material 551, the second active material 552, and acetylene black 553, which are the positive electrode active materials, refer to voids or binders.

[0224] In FIG. 13A, acetylene black 553 is illustrated as a conductive additive. Also, FIG. 13A shows an example in which a second active material 552 having a smaller particle size than the active material 551 is mixed. By mixing particles of different sizes, a high-density positive electrode can be obtained. Note that the active material 551 has a core-shell structure. Here, the "core" does not mean the nucleus of the entire particle, but is used to indicate the positional relationship between the central part and the outer shell of the particle. Also, the "core" can be called the core material. For example, for the active material 551, the first NCM is used for the core and the second NCM is used for the shell. As the first NCM, a LiNi x Co y Mn z O2 composite oxide is used, and as the second NCM, a LiNi x Co y Mn z O2 composite oxide can be used. Note that the atomic ratio of the second NCM is not limited to the above. For example, by making the ratio of nickel smaller than that of the first NCM, the same effect as the above atomic ratio may be obtained.

[0225] Also, in FIG. 13A, the boundary between the core region and the shell region of the active material 551 is indicated by a dotted line inside the particle 551. FIG. 13A shows an example in which the active material 551 is illustrated as spherical, but it is not particularly limited and may have various shapes. The cross-sectional shape of the active material 551 may be elliptical, rectangular, trapezoidal, conical, a square with rounded corners, or an asymmetric shape.

[0226] FIG. 13B shows an example in which the active material 551 is illustrated as having various shapes. FIG. 13B shows an example different from FIG. 13A.

[0227] Also, in the positive electrode of FIG. 13B, graphene 554 is used as the carbon material used as the conductive additive.

[0228] Graphene has electrically, mechanically, or chemically amazing properties, and thus is a carbon material expected to be applied in various fields such as field effect transistors or solar cells using graphene.

[0229] Figure 13B shows a positive electrode active material layer having an active material 551, graphene 554, and acetylene black 553 formed on a current collector 550.

[0230] In the step of mixing graphene 554 and acetylene black 553 to obtain an electrode slurry, the weight of the carbon black to be mixed is preferably 1.5 times or more and 20 times or less, preferably 2 times or more and 9.5 times or less the weight of graphene.

[0231] Also, when the mixing of graphene 554 and acetylene black 553 is within the above range, during slurry preparation, acetylene black 553 has excellent dispersion stability and is less likely to form agglomerated portions. Further, when the mixing of graphene 554 and acetylene black 553 is within the above range, a higher electrode density can be achieved compared to a positive electrode using only acetylene black 553 as a conductive assistant. By increasing the electrode density, the capacity per unit weight can be increased. Specifically, the density of the positive electrode active material layer by weight measurement can be made higher than 3.5 g / cc. Also, when the active material 551 is used for the positive electrode and the mixing of graphene 554 and acetylene black 553 is within the above range, a synergistic effect can be expected for the secondary battery to have a higher capacity, which is preferable.

[0232] These are effective for in-vehicle secondary batteries.

[0233] When the number of secondary batteries is increased and the weight of the vehicle increases, the energy required to move increases, so the cruising range also shortens. By using high-density secondary batteries, the cruising range can be maintained with little change in the total weight of the vehicle equipped with secondary batteries of the same weight.

[0234] In addition, when the secondary battery of a vehicle has a high capacity, a large amount of power is required for charging, so it is desirable to complete charging in a short time. Further, during so-called regenerative charging in which power is temporarily generated when the vehicle brakes and used for charging, charging is performed under high-rate charging conditions, and thus good rate characteristics are required for the secondary battery for vehicles.

[0235] By using the active material 551 for the positive electrode and setting the mixing ratio of acetylene black and graphene within an optimal range, it becomes possible to achieve both densification of the electrode and creation of appropriate gaps necessary for ionic conduction, and a secondary battery for vehicle use with a high energy density and good output characteristics can be obtained.

[0236] In addition, in FIG. 13B, the boundary between the core region and the shell region of the active material 551 is indicated by a dotted line inside the active material 551. In FIG. 13B, the regions not filled with the active material 551, graphene 554, and acetylene black 553 indicate voids or binders. Voids are necessary for the infiltration of the solvent, but if there are too many, the electrode density decreases, and if there are too few, the solvent cannot infiltrate, and they remain as voids even after the secondary battery is formed, resulting in a decrease in efficiency.

[0237] By using the active material 551 for the positive electrode and setting the mixing ratio of acetylene black and graphene within an optimal range, it becomes possible to achieve both densification of the electrode and creation of appropriate gaps necessary for ionic conduction, and a secondary battery with a high energy density and good output characteristics can be obtained.

[0238] FIG. 13C illustrates an example of a positive electrode using carbon nanotubes 555 instead of graphene. FIG. 13C shows an example different from FIG. 13B. When carbon nanotubes 555 are used, aggregation of acetylene black 553, which is a type of carbon black, can be prevented and dispersibility can be improved.

[0239] In FIG. 13C, the regions not filled with the active material 551, carbon nanotubes 555, and acetylene black 553 indicate voids or binders.

[0240] Further, as another example of the positive electrode, FIG. 13D is illustrated. FIG. 13D shows an example in which the active material 551 does not have a core-shell structure. Further, FIG. 13D shows an example in which carbon nanotubes 555 are used in addition to graphene 554. When both graphene 554 and carbon nanotubes 555 are used, aggregation of acetylene black 553, which is a kind of carbon black, can be prevented and the dispersibility can be further enhanced.

[0241] In FIG. 10D, the region not filled with the active material 551, the carbon nanotubes 555, the graphene 554, and the acetylene black 553 refers to voids or a binder.

[0242] By using any one of the positive electrodes of FIGS. 13A, 13B, 13C, and 13D, stacking the electrolyte 1010 on the positive electrode, and placing the laminate with the negative electrode stacked on the electrolyte 1010 in a container (outer package, metal can) that houses the laminate, a semi-solid secondary battery can be manufactured.

[0243] Further, although the above configuration shows an example of a semi-solid secondary battery, it is not particularly limited, and it may be a secondary battery using a solvent. In the case of a secondary battery using a solvent, a separator is stacked on the positive electrode, the laminate with the negative electrode stacked on the separator is placed in a container (outer package, metal can) that houses the laminate, and the container is filled with the solvent to manufacture the secondary battery.

[0244] In this specification and the like, a polymer electrolyte secondary battery refers to a secondary battery having a polymer in the electrolyte layer between the positive electrode and the negative electrode. Polymer electrolyte secondary batteries include dry (or true) polymer electrolyte batteries and polymer gel electrolyte batteries. Further, the polymer electrolyte secondary battery may be referred to as a semi-solid battery.

[0245] When a semi-solid battery is manufactured using the active material 551, the semi-solid battery becomes a secondary battery with a large charge-discharge capacity. Further, a semi-solid battery with a high charge-discharge voltage can be obtained. Alternatively, a semi-solid battery with high safety or reliability can be realized.

[0246] This embodiment can be freely combined with other embodiments.

[0247] (Embodiment 6) In this embodiment, an example of mounting a control system for a secondary battery, which is one aspect of the present invention, on a vehicle, a moving body, etc. will be described.

[0248] Examples of electric vehicles using one aspect of the present invention are shown in FIGS. 14A, 14B, 14C, and 14D. The automobile 2001 shown in FIG. 14A is an electric vehicle that uses an electric motor as a power source for running. Alternatively, it is a hybrid vehicle that can appropriately select and use an electric motor and an engine as power sources for running. When mounting a secondary battery on a vehicle, the low-temperature secondary battery, temperature sensor, and heater shown in Embodiment 1 are mounted. Further, by using the semi-solid secondary battery described in Embodiment 5, a synergistic effect on safety can be obtained. The automobile 2001 shown in FIG. 14A has a battery pack 2200, and the battery pack has a secondary battery module in which a plurality of secondary batteries are connected. Furthermore, it preferably has a temperature control system for the secondary battery that is electrically connected to the secondary battery module. By preparing a low-temperature secondary battery as an auxiliary power source and providing heating means for heating a part of the main power source secondary battery, a control system for the secondary battery that is less affected by the ambient temperature can be mounted on the automobile 2001.

[0249] In addition, the automobile 2001 can be charged by receiving power supply from an external charging facility by a plug-in method or a non-contact power supply method or the like to the secondary battery that the automobile 2001 has. At the time of charging, the charging method, the standard of the connector, etc. may be appropriately carried out in a predetermined method such as CHAdeMO (registered trademark) or Combo. The secondary battery may be a charging station provided in a commercial facility or may be a household power source. For example, by plug-in technology, the low-temperature secondary battery and the secondary battery mounted on the automobile 2001 can be charged by external power supply. Charging can be performed by converting AC power into DC power via a conversion device such as an AC-DC converter.

[0250] Further, although not shown, a power receiving device can be mounted on a vehicle, and power can be supplied and charged non - contactlessly from a power transmission device on the ground. In the case of this non - contact power supply method, by incorporating the power transmission device into a road or an outer wall, charging can be performed not only while the vehicle is stopped but also while it is running. Also, using this non - contact power supply method, power can be transmitted and received between two vehicles. Furthermore, a solar cell can be provided on the exterior of the vehicle to charge the secondary battery when the vehicle is stopped or running. For such non - contact power supply, an electromagnetic induction method or a magnetic field resonance method can be used.

[0251] FIG. 14B shows a large transport vehicle 2002 having an electrically controlled motor as an example of a transport vehicle. The secondary battery module of the transport vehicle 2002 has, for example, four secondary batteries with a voltage of 3.5V or more and 4.7V or less as a cell unit, and has a maximum voltage of 170V with 48 cells connected in series. Since it has the same functions as FIG. 14A except for the number of secondary batteries constituting the secondary battery module of the battery pack 2201, the description is omitted. By preparing a secondary battery for low temperature as an auxiliary power source and providing heating means for heating a part of the secondary battery of the main power source, a control system for a secondary battery that is less affected by the ambient temperature can be mounted on the large transport vehicle 2002.

[0252] FIG. 14C shows a large transport vehicle 2003 having an electrically controlled motor as an example. The secondary battery module of the transport vehicle 2003 has a maximum voltage of 600V with, for example, 100 or more secondary batteries with a voltage of 3.5V or more and 4.7V or less connected in series. Therefore, secondary batteries with small characteristic variations are required. Since it has the same functions as FIG. 14A except for the number of secondary batteries constituting the secondary battery module of the battery pack 2202, the description is omitted. By preparing a secondary battery for low temperature as an auxiliary power source and providing heating means for heating a part of the secondary battery of the main power source, a control system for a secondary battery that is less affected by the ambient temperature can be mounted on the large transport vehicle 2003.

[0253] FIG. 14D shows an aircraft 2004 having an engine that burns fuel as an example. Since the aircraft 2004 shown in FIG. 14D has wheels for takeoff and landing, it can also be said to be part of a transport vehicle. It has a battery pack 2203 that includes a plurality of secondary batteries connected to form a secondary battery module and a charge control device. The secondary battery for low temperature, a temperature sensor, and a heater shown in Embodiment 2 are mounted.

[0254] The secondary battery module of the aircraft 2004 has a maximum voltage of 32V by connecting, for example, eight 4V secondary batteries in series. Since it has the same functions as those in FIG. 14A except for the number of secondary batteries constituting the secondary battery module of the battery pack 2203, the description thereof is omitted. By preparing a secondary battery for low temperature as an auxiliary power source and providing heating means for heating a part of the secondary battery of the main power source, a control system for a secondary battery that is less affected by the ambient temperature can be mounted on the aircraft 2004.

[0255] This embodiment can be freely combined with other embodiments.

Description of Reference Numerals

[0256] 10: Secondary battery for low temperature, 11a: Secondary battery, 11b: Secondary battery, 11c: Secondary battery, 11d: Secondary battery, 11e: Secondary battery, 101: Secondary battery for low temperature, 102a: Secondary battery, 102b: Secondary battery, 102c: Secondary battery, 102d: Secondary battery, 102e: Secondary battery, 103a: Switch, 103b: Switch, 103c: Switch, 103d: Switch, 103e: Switch, 150a: Heater, 150b: Heater, 150c: Heater, 150d: Heater, 150e: Heater, 401: Secondary battery for low temperature, 402a: Secondary battery, 402n: Secondary battery, 403a: Switch, 403b: Switch, 403c: Switch, 403n: Switch, 405a: Temperature sensor, 405b: Temperature sensor, 405n: Temperature sensor, 406a: Monitoring circuit, 406b: Monitoring circuit, 406n: Monitoring circuit, 450a: Heater, 450b: Heater, 450n: Heater, 500: Secondary battery, 501: Positive current collector, 502: Positive active material layer, 503: Positive electrode, 504: Negative current collector, 505: Negative active material layer, 506: Negative electrode, 507: Separator, 508: Electrolyte, 509: Outer package, 510: Positive lead electrode, 511: Negative lead electrode, 600: Secondary battery, 601: Positive cap, 602: Battery can, 603: Positive terminal, 604: Positive electrode, 605: Separator, 606: Negative electrode, 607: Negative terminal, 608: Insulating plate, 609: Insulating plate, 611: PTC element, 612: Safety valve mechanism, 613: Conductive plate, 614: Conductive plate, 615: Module, 616: Conductive wire, 617: Heater, 911a: Terminal, 911b: Terminal, 913: Secondary battery, 930: Housing, 930a: Housing, 930b: Housing, 931: Negative electrode, 931a: Negative active material layer, 932: Positive electrode, 932a: Positive active material layer, 933: Separator, 950: Wound body, 950a: Wound body, 951: Terminal, 952: Terminal, 1000: Secondary battery, 1001: Positive current collector, 1002: Positive active material layer, 1003: Electrolyte layer, 1004: Negative active material layer, 1005: Negative current collector, 1006: Positive electrode, 1007: Negative electrode, 1010: Electrolyte, 1011: Positive active material, 1015: Inorganic filler, 1301a: Secondary battery, 1301b: Secondary battery, 1302: Control circuit, 1303: Motor controller, 1304: Motor, 1305: Gear, 1306: DCDC circuit, 1307: Electric power steering, 1308a: Heater, 1308b: Heater,1309: Defogger, 1310: DCDC Circuit, 1311: Secondary Battery, 1312: Inverter, 1313: Audio, 1314: Power Window, 1315: Lamps, 1316: Tires, 1317: Rear Motor, 1320a: Monitoring Circuit, 1320b: Monitoring Circuit, 1321: Monitoring Circuit, 1322: Switch, 1323: Switch

Claims

1. A control system for a secondary battery, comprising a control circuit, first to third secondary batteries, first to third switches, and first to third heaters, wherein: The first secondary battery is not connected to the second secondary battery and the third secondary battery; The second secondary battery is connected in series with the third secondary battery; At least a part of the operating temperature range of the first secondary battery overlaps with the operating temperature ranges of the second secondary battery and the third secondary battery; The viscosities of the electrolytes of the second secondary battery and the third secondary battery are lower than the viscosity of the electrolyte of the first secondary battery, respectively; The control circuit turns on the first switch to heat the first heater using the first secondary battery as a power source; When the second secondary battery reaches a first temperature due to the heating of the first heater, the control circuit turns off the first switch; The control circuit turns on the second switch to heat the second heater using the second secondary battery as a power source; When the second secondary battery reaches a second temperature due to the heating of the second heater, the control circuit turns off the second switch; The control circuit turns on the third switch to heat the third heater using the third secondary battery as a power source.

2. The control system for a secondary battery according to claim 1, wherein: The electrolyte of the first secondary battery comprises ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate.

3. The control system for a secondary battery according to claim 1 or claim 2, wherein: The electrolytes of the second secondary battery and the third secondary battery comprise diethyl carbonate and ethylene carbonate.

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