Storage battery, battery unit, and battery monitoring device

Abstract

A storage battery (10) is provided with a positive electrode layer, a negative electrode layer, and a separator provided between the positive electrode layer and the negative electrode layer. The spacer is provided in a form containing a substance whose dielectric constant varies according to temperature. The battery cell (30) is provided with: a calculation unit (31) that applies an AC signal to the positive electrode terminal (14) and the negative electrode terminal (15) of the storage battery (10) and calculates a dielectric constant or a capacitor capacity on the basis of a response signal thereof; and a temperature monitoring unit (32) that monitors the internal temperature of the battery (10) on the basis of the dielectric constant or the capacitor capacity calculated by the calculation unit (31).

Description

Citation of related applications

[0001] This application is based on Japanese Patent Application No. 2022-139443 filed on September 1, 2022, and the contents thereof are incorporated herein by reference. Technical Field

[0002] The disclosure in this specification relates to a storage battery, a battery cell, and a battery monitoring device. Background Art

[0003] In the past, various technologies for monitoring the internal temperature of batteries (secondary batteries) such as lithium-ion batteries have been proposed. As such a technology, for example, there is known a technology that has an outer surface temperature detection unit that detects the outer surface temperature of the battery, a current detection unit that detects the charge and discharge current of the battery, and an internal resistance estimation unit that estimates the internal resistance of the battery, and estimates the internal temperature of the battery based on the outer surface temperature, charge and discharge current, and internal resistance of these batteries (for example, refer to Patent Document 1). In addition, the following technology is known: in a battery pack having a plurality of battery cells, temperature sensors are only provided in battery cells at specific positions (for example, both end positions and a central position) among all the battery cells, and the temperature of the battery cells without temperature sensors is estimated by linear interpolation of the temperature detection values ​​of these temperature sensors. Prior art literature Patent Literature

[0004] Patent Document 1: Japanese Patent Application Publication No. 2018-170144 Summary of the invention

[0005] However, the prior art does not directly detect the internal temperature of the battery, but estimates the internal temperature using the detected value of the external surface temperature of the battery, and therefore, a detection delay occurs due to the time required for heat transfer from the inside to the outside of the battery. Therefore, for example, when a temperature change occurs inside the battery, there is a possibility that a delay occurs before the temperature change can be grasped. For example, in a battery, it is considered that thermal runaway may occur due to some reason, and when the thermal runaway occurs, it is desired to perform appropriate processing as soon as possible.

[0006] The present disclosure has been made in view of the above circumstances, and a main object of the present disclosure is to provide a storage battery, a battery cell, and a battery monitoring device that can detect the internal temperature as quickly as possible.

[0007] The various methods disclosed in this specification use different technical means to achieve various purposes. The purposes, features and effects disclosed in this specification can be more clearly understood by referring to the subsequent detailed description and drawings.

[0008] Method 1 is a storage battery. The battery comprises a positive electrode layer, a negative electrode layer and a separator disposed between the positive electrode layer and the negative electrode layer. The spacer is provided in a form containing a substance whose dielectric constant changes according to temperature.

[0009] In the storage battery, since the spacer is provided in a form containing a material whose dielectric constant changes according to temperature, the internal temperature of the storage battery can be detected by measuring the dielectric constant or its related value. In this case, for example, when the temperature changes inside the storage battery, the temperature change can be directly grasped as a change in the dielectric constant inside the battery. As a result, a storage battery capable of detecting the internal temperature as quickly as possible can be realized.

[0010] In the second embodiment, ferroelectric is used as the substance. In this case, by adding ferroelectric to the structure of the spacer, the dielectric constant can be increased, and the sensitivity of temperature detection can be improved. In the third embodiment, the spacer melts when the inside of the battery reaches a predetermined melting temperature, and as the substance, a ferroelectric having a maximum dielectric constant and a Curie temperature at or near the melting temperature of the spacer is used.

[0012] In a battery, as a process when thermal runaway occurs with a rise in internal temperature, the melting of the separator, thermal decomposition of the positive electrode, generation of internal gas, and thermal runaway occur in sequence. In this case, if the internal temperature of the battery rises and reaches the melting temperature of the separator or near it, a sudden change in the dielectric constant of the battery (a sudden change in the capacitor capacity) will occur. Here, by understanding the sudden change in the dielectric constant, it is possible to quickly understand the situation in which thermal runaway of the battery may occur.

[0013] In method 4, it includes: a battery according to any one of methods 1 to 3; a calculation unit, which applies an AC signal to the positive electrode layer and the negative electrode layer and calculates the dielectric constant or capacitor capacity based on the response signal; and a temperature monitoring unit, which monitors the internal temperature of the battery based on the dielectric constant or capacitor capacity calculated by the calculation unit.

[0014] In a structure in which the dielectric constant changes according to the temperature in the battery, the capacitor capacity between the positive electrode layer and the negative electrode layer changes according to the temperature. On the other hand, according to the electrochemical impedance measurement method (AC impedance method), it is possible to apply an AC signal to the positive electrode layer and the negative electrode layer and obtain the frequency characteristics of the impedance, and calculate the capacitor capacity of the battery based on the frequency characteristics of the impedance. In this case, by applying an AC signal to the positive electrode layer and the negative electrode layer and calculating the dielectric constant or capacitor capacity, and using the dielectric constant or capacitor capacity for battery monitoring, the internal temperature of the battery can be grasped ideally.

[0015] In method 5, in the above-mentioned storage battery, the above-mentioned spacer melts due to the fact that the inside of the battery reaches a prescribed melting temperature, and as the above-mentioned substance, a ferroelectric whose Curie temperature has a maximum dielectric constant and is the melting temperature of the above-mentioned spacer or a temperature near it is used, and the above-mentioned temperature monitoring unit determines whether the internal temperature of the above-mentioned storage battery rises to a prescribed temperature determined as the melting temperature of the above-mentioned spacer or a temperature near it based on the dielectric constant or capacitor capacity calculated by the above-mentioned calculation unit.

[0016] In the above structure, it is possible to appropriately determine whether the internal temperature of the battery has risen to the melting temperature of the separator or a temperature close thereto based on the dielectric constant or capacitor capacity of the battery. Thus, it is possible to quickly grasp the possibility of thermal runaway of the battery and appropriately perform processing such as notifying the user.

[0017] In method 6, in the above-mentioned storage battery, the above-mentioned substance includes a plurality of substances with different Curie temperatures having maximum values ​​of the dielectric constant, and a unique correlation between temperature and the dielectric constant or the capacitor capacity is determined within a specified temperature range including the Curie temperatures of these substances. The above-mentioned temperature monitoring unit uses the above-mentioned correlation and estimates the internal temperature of the above-mentioned storage battery based on the dielectric constant or the capacitor capacity calculated by the above-mentioned calculation unit.

[0018] In a storage battery, when a plurality of substances having different Curie temperatures are added to a spacer, a unique correlation between temperature and dielectric constant or capacitor capacity can be determined within a predetermined temperature range including the Curie temperatures of the substances. That is, the change in dielectric constant or capacitor capacity corresponding to the internal temperature of the storage battery can be quantified. Furthermore, by using this correlation, the internal temperature of the storage battery can be estimated based on the dielectric constant or capacitor capacity.

[0019] In method 7, it includes: a temperature determination unit that determines whether the internal temperature of the battery is the same as the external temperature outside the battery; and a correction value calculation unit that, when it is determined that the temperature of the battery is the same as the external temperature, calculates a correction value for correcting the correlation by comparing the external temperature under the condition with the internal temperature of the battery estimated by the temperature monitoring unit.

[0020] For example, when a battery is left unused for a long time, the internal temperature of the battery is the same as the external temperature. In this case, by comparing the internal temperature (estimated temperature) of the battery with the external temperature, the deviation of the correlation between the temperature and the dielectric constant or the capacitor capacity can be grasped. In view of this, according to the above structure, by calculating a correction value for correcting the correlation and using the correction value to appropriately correct the correlation, the accuracy of the temperature estimation in the battery can be improved.

[0021] Mode 8 is a battery monitoring device, the battery monitoring device is suitable for a storage battery, The battery includes a positive electrode layer, a negative electrode layer, and a separator disposed between the positive electrode layer and the negative electrode layer, wherein the separator is disposed in a form containing a material whose dielectric constant changes according to temperature. The battery monitoring device comprises: a calculation unit that applies an AC signal to the positive electrode layer and the negative electrode layer and calculates a dielectric constant or a capacitor capacity based on a response signal thereof; and A temperature monitoring unit monitors an internal temperature of the battery based on the dielectric constant or capacitor capacity calculated by the calculation unit.

[0022] In a structure in which the dielectric constant changes according to the temperature in the battery, the capacitor capacity between the positive electrode layer and the negative electrode layer changes according to the temperature. On the other hand, according to the electrochemical impedance measurement method (AC impedance method), it is possible to apply an AC signal to the positive electrode layer and the negative electrode layer and obtain the frequency characteristics of the impedance, and calculate the capacitor capacity of the battery based on the frequency characteristics of the impedance. In this case, by applying an AC signal to the positive electrode layer and the negative electrode layer and calculating the dielectric constant or capacitor capacity, and using the dielectric constant or capacitor capacity for battery monitoring, the internal temperature of the battery can be ideally grasped. In addition, the internal temperature can be detected as quickly as possible.

[0023] Method 9 is a battery monitoring device applicable to a battery recorded in any one of methods 1 to 3, comprising: an AC signal applying unit, which applies an AC signal having a frequency higher than the AC frequency corresponding to a zero-crossing point at which the imaginary part of the complex impedance characteristic of the battery is zero to the positive electrode layer and the negative electrode layer of the battery; a calculation unit, which calculates the dielectric constant in the spacer based on a response signal thereof when the AC signal is applied by the AC signal applying unit; and a temperature monitoring unit, which monitors the internal temperature of the battery based on the dielectric constant calculated by the calculation unit.

[0024] In a battery in which a ferroelectric is attached to a spacer, the dielectric constant of the ferroelectric changes according to the temperature of the battery. In addition, it was found that by applying an AC signal with a frequency higher than the AC frequency corresponding to the zero-crossing point (real component with an imaginary part of zero) in the complex impedance characteristic to the battery, a value corresponding to the dielectric constant of the ferroelectric can be obtained as the real part of the complex impedance. In this case, by finding the dielectric constant of the ferroelectric based on the real part of the complex impedance, the temperature of the battery can be estimated based on the dielectric constant.

[0025] In view of this, an AC signal having a frequency higher than the AC frequency corresponding to the zero-crossing point in the complex impedance characteristic of the battery is applied to the positive electrode layer and the negative electrode layer of the battery, and the dielectric constant in the spacer is calculated based on the response signal obtained in this state. Then, the internal temperature of the battery is monitored based on the calculated dielectric constant. In this way, the internal temperature of the battery can be ideally grasped.

[0026] In aspect 10, the AC signal applying unit applies an AC signal in a frequency range of 20 to 800 kHz as the AC signal.

[0027] In a battery, since the AC frequency corresponding to the zero-crossing point in the complex impedance characteristic is about 1 to 10 kHz, the frequency of the AC signal when calculating the dielectric constant in the spacer is set to 20 to 800 kHz. In this case, the change in the dielectric constant of the spacer with temperature can be appropriately understood.

[0028] In method 11, the AC signal applicator applies an AC signal of a first frequency and an AC signal of a second frequency higher than the first frequency for measuring the complex impedance characteristics near the zero-crossing point, respectively, and the calculator calculates the internal resistance of the battery based on the response signal of the state in which the AC signal of the first frequency is applied, and on the other hand, calculates the dielectric constant in the spacer based on the response signal of the state in which the AC signal of the second frequency is applied.

[0029] The AC signal applying section applies an AC signal of a first frequency for measuring the complex impedance characteristics near the zero crossing point and an AC signal of a second frequency higher than the first frequency. Then, the internal resistance of the battery is calculated based on the response signal of the state in which the AC signal of the first frequency is applied, and on the other hand, the dielectric constant in the spacer is calculated based on the response signal of the state in which the AC signal of the second frequency is applied. In this case, it is possible to appropriately perform the calculation of these internal resistances and the calculation of the dielectric constant while distinguishing between the use of an AC frequency suitable for calculating the internal resistance of the battery and an AC frequency suitable for calculating the dielectric constant of the spacer.

[0030] In method 12, in the above-mentioned storage battery, the above-mentioned separator melts due to the fact that the inside of the battery reaches a specified melting temperature, and the above-mentioned calculation unit increases the calculation frequency of the above-mentioned dielectric constant when the temperature of the above-mentioned storage battery is higher than a specified temperature lower than the above-mentioned melting temperature, compared with a case where the temperature is lower than the above-mentioned specified temperature.

[0031] In a structure in which a material (ferroelectric) whose dielectric constant changes according to temperature is added to the spacer, the temperature characteristics of the dielectric constant can be used to determine whether the internal temperature of the battery reaches the melting temperature of the spacer or is close to the melting temperature of the spacer. On the other hand, when the dielectric constant is calculated based on the calculation result of the complex impedance, the calculation load and power consumption may increase. In view of this, when the temperature of the battery is higher than a specified temperature lower than the melting temperature, the calculation frequency of the dielectric constant is increased compared to the case where the temperature is lower than the specified temperature. As a result, in the normal state of the battery, the calculation frequency of the dielectric constant is relatively low, which can achieve a reduction in the calculation load and power consumption, and in the case of possible thermal runaway, the detection sensitivity of the temperature rise can be temporarily increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The above objects, other objects, features and advantages of the present disclosure will become more apparent with reference to the accompanying drawings and the following detailed description. Figure 1 It is a three-dimensional diagram of a battery. Figure 2 It is a perspective view of a wound body constituting a storage battery. Figure 3 This is a graph showing the temperature characteristics of the dielectric constant in a ferroelectric. Figure 4 It is a diagram showing a schematic structure of a battery unit including a storage battery. Figure 5 : is a flowchart showing the battery temperature monitoring process. Figure 6 is a graph showing the temperature characteristics of the dielectric constant. Figure 7 : is a flowchart showing the correction value calculation process in the second embodiment. Figure 8 This is a graph showing the temperature characteristics of the relative dielectric constant in a ferroelectric. Fig. 9 This is a diagram showing an example of a complex impedance plane diagram of a storage battery. Fig.10 : is a graph showing the relationship between the frequency f and the real number part Re_Z. Fig.11 is a diagram showing an equivalent circuit of a storage battery. Fig.12It is a diagram showing the configuration of a control device in a third embodiment. Fig.13 : is a flowchart showing the battery temperature monitoring process in the third embodiment. Fig.14 It is a diagram showing the relationship between the real part Re_Z and the relative dielectric constant εr. Fig.15 : is a flowchart showing a battery temperature monitoring process in a modified example. DETAILED DESCRIPTION

[0033] The following is an explanation of the embodiment based on the accompanying drawings. In this embodiment, a lithium ion storage battery is used as a secondary battery, and a specific structure using the lithium ion storage battery is explained. In addition, in each of the following embodiments, the same or equivalent parts are marked with the same symbols in the drawings, and the description of the parts with the same symbols is cited.

[0034] (First Embodiment) Figure 1 is a perspective view of a lithium ion secondary battery 10 according to this embodiment. Figure 2 It is a perspective view of the winding body 21 which comprises the lithium ion secondary battery 10. In addition, in the following description, the lithium ion secondary battery 10 is simply referred to as the secondary battery 10.

[0035] exist Figure 1 In the figure, the storage battery 10 has a frame 11 and a winding body 21 accommodated in the frame 11. The frame 11 is in the shape of a flat rectangular parallelepiped, for example, made of a metal material or a resin material. The frame 11 has a main body 12 and a cover 13 that can be assembled on the opening side of the main body 12, and a closed space for accommodating the winding body 21 is formed by these main body 12 and cover 13. The winding body 21 is accommodated in the frame 11 in a state of being immersed in an electrolyte. The frame 11 has: a positive terminal 14 and a negative terminal 15 for external connection; and a safety valve 16, which opens when the internal pressure of the frame 11 rises to a specified level to release the internal pressure.

[0036] like Figure 2 As shown, the winding body 21 is formed by stacking the positive electrode layer 22, the negative electrode layer 23 and the separator 24. Specifically, the positive electrode layer 22, the negative electrode layer 23 and the separator 24 are respectively formed into sheets, and they are stacked on each other to form a laminated sheet. Moreover, the winding body 21 is formed by winding the laminated sheet composed of the positive electrode layer 22, the negative electrode layer 23 and the separator 24 into a flat shape. In the laminated sheet, the positive electrode layer 22, the separator 24, the negative electrode layer 23, and the separator 24 are stacked in sequence into four layers, and by winding the laminated sheet, the separator 24 is sandwiched between the positive electrode layer 22 and the negative electrode layer 23.

[0037] The positive electrode layer 22 is formed of a positive electrode active material layer composed of, for example, a lithium transition metal oxide. As the positive electrode active material, for example, Li(Co1 / 3Ni1 / 3Mn1 / 3)O2, LiNiO2, LiMn2O4, LiCoO2, LiFePO4, etc. can be used. The negative electrode layer 23 is formed of a negative electrode active material layer composed of, for example, a carbon material.

[0038] The separator 24 is an insulating sheet having ion conductivity and is specifically formed of a polyolefin layer such as polypropylene (PP), polyethylene (PE), or a combination of compounds thereof.

[0039] The wound body 21 includes a positive electrode collector 26 made of aluminum foil or the like and a negative electrode collector 27 made of copper foil or the like. When the wound body 21 is housed in the frame 11, the positive electrode collector 26 is electrically connected to the positive electrode terminal 14, and the negative electrode collector 27 is electrically connected to the negative electrode terminal 15.

[0040] In addition, in the battery 10, the internal temperature may rise excessively and cause thermal runaway. In this case, as the internal temperature rises, the melting of the separator 24, the thermal decomposition of the positive electrode layer 22, the generation of internal gas, and thermal runaway occur in sequence. In the case where this thermal runaway may occur, it is desired to grasp the rise in the internal temperature of the battery 10 as soon as possible. Therefore, in the present embodiment, a ferroelectric is added to the separator 24 of the battery 10 as a substance whose dielectric constant changes according to temperature, and the dielectric constant is grasped by measurement, etc., so that the internal temperature of the battery 10 can be detected. In the present embodiment, barium titanate (BaTiO3) is used as the ferroelectric.

[0041] Figure 3 is a graph showing the temperature characteristics of the dielectric constant in a ferroelectric. Figure 3 As shown, ferroelectrics have the property that the dielectric constant takes a maximum value at a plurality of specific temperatures (Curie temperatures). In the present embodiment, by making the spacer 24 contain a ferroelectric, a prescribed temperature characteristic is applied to the spacer 24. On the sheet-like spacer 24, a ferroelectric is attached to one or both surfaces of the sheet surface on both sides of the front and back. Specifically, it is conceivable to attach a particle-like ferroelectric to the sheet surface of the spacer 24 by coating. The ferroelectric may also be buried (contained) inside the spacer 24.

[0042] Here, the separator 24 melts because the battery reaches a predetermined melting temperature (around 120 to 140°C). On the other hand, one of the Curie temperatures at which the electric constant of the ferroelectric added to the separator 24 reaches a maximum value is the melting temperature of the separator 24 or a temperature near it. Figure 3Among the multiple local maximum values, "A" is a local maximum value corresponding to the melting temperature of the spacer 24. In this case, when thermal runaway occurs in the battery 10, if the internal temperature of the battery 10 rises and reaches the melting temperature of the spacer 24 or its vicinity, a sudden change in the dielectric constant of the battery 10 (a sudden change in the capacitor capacity) occurs.

[0043] Figure 4 1 is a diagram showing a schematic structure of a battery unit 30 including a storage battery 10. Figure 4 In the embodiment, the battery unit 30 includes: a calculation unit 31, which is connected to the positive terminal 14 and the negative terminal 15 of the storage battery 10 and calculates the capacitor capacity of the storage battery 10 based on the electrical information input from these terminals 14 and 15; a temperature monitoring unit 32, which monitors the internal temperature of the storage battery 10 based on the capacitor capacity calculated by the calculation unit 31; and a notification unit 33, which notifies the user etc. based on the monitoring result obtained by the temperature monitoring unit 32. These parts are processing functions realized by the control device 40 composed of a microcomputer or the like. In the control device 40, the microcomputer is composed of a CPU (computing device) or a storage device (various memories), and various functions are realized by executing the program stored in the storage device. Various functions can be realized by an electronic circuit as hardware, or by both hardware and software. The control device 40 is equivalent to a "battery monitoring device".

[0044] The calculation unit 31 applies an AC signal to the positive terminal 14 and the negative terminal 15 while monitoring the temperature of the storage battery 10, and calculates the capacitor capacity based on the response signal thereof. In the present embodiment, an electrochemical impedance measurement method (AC impedance method) is used to apply an AC voltage to the positive terminal 14 and the negative terminal 15, and the capacitor capacity of the storage battery 10 is calculated based on the frequency characteristics of the complex impedance obtained from the AC voltage and the AC current as the response signal thereof. In addition, an AC current may be applied as the AC signal. The dielectric constant may also be calculated by using the correlation between the capacitor capacity and the dielectric constant.

[0045] In addition, the temperature monitoring unit 32 determines whether the internal temperature of the battery 10 has risen to a predetermined temperature (e.g., 120° C.) corresponding to the melting temperature of the spacer 24 based on the capacitor capacity. The notification unit 33 notifies, based on the monitoring result obtained by the temperature monitoring unit 32, that, for example, thermal runaway of the battery 10 may occur, for example, by sound, screen display, lamp display, etc.

[0046] Figure 5 2 is a flowchart showing the temperature monitoring process of the battery 10 . This process is executed by the control device 40 at a predetermined cycle.

[0047] exist Figure 5In step S11, the capacitor capacity of the storage battery 10 is calculated. At this time, as described above, the AC impedance method is used to apply an AC signal to the positive terminal 14 and the negative terminal 15, and the capacitor capacity is calculated based on the response signal.

[0048] Then, in step S12, it is determined whether the internal temperature of the battery 10 has risen to a predetermined temperature (e.g., 120° C.) corresponding to the melting temperature of the spacer 24, based on whether the capacitor capacity calculated in step S11 is greater than a predetermined value. At this time, if the capacitor capacity of the battery 10 is a capacitor capacity corresponding to a dielectric constant that becomes a maximum value in the temperature characteristic of the dielectric constant, it is considered that the internal temperature of the battery 10 has risen to a temperature corresponding to the melting temperature of the spacer 24, and step S12 is affirmed, and the process proceeds to step S13. In step S13, a user or the like is notified that thermal runaway of the battery 10 may occur.

[0049] According to the present embodiment described in detail above, the following excellent effects can be obtained.

[0050] In the storage battery 10, since the spacer 24 is provided in a form containing a substance (ferroelectric) whose dielectric constant changes according to temperature, the internal temperature of the storage battery 10 can be detected by measuring the dielectric constant or the capacitor capacity which is a related value thereof. In this case, when the temperature changes inside the storage battery 10, the temperature change can be directly grasped as a change in the dielectric constant inside the battery. As a result, the storage battery 10 that can detect the internal temperature as quickly as possible can be realized.

[0051] Compared with the existing structure, the battery 10 of this embodiment does not force the electrode material of the battery 10 to change, and can maintain the existing state. Here, the electrode material will affect the energy capacity and output density of the battery, and the time-dependent degradation of these performances, and it takes a huge amount of development time to adjust. Therefore, when adding new substances to the electrode material, in order to maintain the same performance, it is necessary to spend a huge amount of development time again. In contrast, as described above, if the structure is to add a ferroelectric to the spacer 24, the above disadvantages can be avoided.

[0052] By forming a structure in which a ferroelectric is added to the spacer 24, the dielectric constant can be increased, thereby improving the sensitivity of temperature detection.

[0053] The spacer 24 is configured to have a ferroelectric material having a maximum dielectric constant and a Curie temperature at or near the melting temperature of the spacer 24. In this case, by understanding the sudden change in dielectric constant, the possibility of thermal runaway of the battery 10 can be understood as soon as possible.

[0054] By applying an AC signal to the positive electrode layer 22 and the negative electrode layer 23 and calculating the capacitor capacity (or dielectric constant), and using the capacitor capacity for battery monitoring, it is possible to ideally grasp the internal temperature of the battery 10. In addition, based on the capacitor capacity, it is determined whether the internal temperature of the battery 10 has risen to a predetermined temperature determined as the melting temperature of the spacer 24 or a temperature in the vicinity thereof, so that it is possible to grasp the situation in which thermal runaway of the battery 10 may occur as soon as possible, and appropriately perform processing such as notifying the user.

[0055] Compared with the prior art, in the prior art, as information related to the heat inside the battery, it is necessary to obtain information from a temperature sensor outside the battery or a sensor that detects the pressure or composition of gas released to the outside of the battery during thermal runaway. In contrast, in the present embodiment, even without a temperature sensor or a gas sensor outside the battery, it is possible to ideally obtain information related to the heat inside the battery based on the capacitor capacity of the storage battery 10.

[0056] (Second Embodiment) In the second embodiment, in the battery 10, as described above, a ferroelectric is added to the spacer 24. In addition, in this embodiment, in particular, the change in the dielectric constant or the change in the capacitor capacity corresponding to the internal temperature of the battery 10 is quantified, and the internal temperature of the battery 10 is estimated based on the dielectric constant information or the capacity information obtained from the battery 10. 上

[0057] Here, as the ferroelectric material added to the spacer 24, a plurality of materials having different Curie temperatures and having maximum dielectric constants are contained in advance. Figure 6 As shown in (a), in the storage battery 10, the dielectric constant changes to a maximum value at different temperatures T1 to T3 for each substance. In this case, the temperatures T1 to T3 at which the maximum values ​​occur are preferably equally spaced. However, the temperature interval may be narrower on the low temperature side than on the high temperature side. Or, conversely, the temperature interval may be wider on the low temperature side than on the high temperature side. The maximum value of the dielectric constant may also occur at 2 or 4 or more temperatures.

[0058] In addition, if Figure 6 As shown in (b), the size of the maximum value is different for each substance, and the characteristic relative to temperature is made gentle (flattened), and on this basis, adjustment is made to obtain the temperature characteristic of the composite dielectric constant obtained by synthesizing the temperature characteristics of each dielectric constant. Through this adjustment, it is possible to obtain Figure 6 The relationship shown in (c).

[0059] according to Figure 6(c) determines a unique correlation between temperature and dielectric constant in a specified temperature range RT including the above-mentioned temperatures T1 to T3. The temperature range RT is preferably a range including the operating temperature range of the battery 10. In addition, the temperature range RT is preferably a range including the operating temperature range of the battery 10 and the melting temperature of the spacer 24. Since the dielectric constant is proportional to the capacitor capacity, the unique correlation between temperature and capacitor capacity can also be predetermined.

[0060] In addition, by mixing additives such as shifters or inhibitors in ferroelectrics, the maximum value of the dielectric constant can be shifted to the low temperature side or the maximum value can be flattened. As a shifter, for example, Ba2+ of barium titanate substituted by Sr2+, Ca2+, etc., or a shifter substituted by Sn4+, Zr4+, etc. for Ti4+ can be used. As an inhibitor, CaTiO3, MgTiO3, etc. can be used.

[0061] In the battery cell 30 of the present embodiment, Figure 4 In the calculation unit 31, the dielectric constant of the battery 10 is calculated. The temperature monitoring unit 32 uses Figure 6 The internal temperature of the battery 10 is estimated based on the dielectric constant calculated by the calculation unit 31. In the present embodiment, the control device 40 calculates the correction factor for the battery 10 when the internal temperature of the battery 10 is the same as the external temperature. Figure 6 Although omitted in the figure, the control device 40 is Figure 4 In addition to the structure shown, it also has a temperature determination unit and a correction value calculation unit.

[0062] Figure 7 1 is a flowchart showing a process of calculating a correction value in the temperature monitoring process according to the present embodiment. This process is executed by the control device 40 at a predetermined cycle.

[0063] exist Figure 7 In step S21, it is determined whether the internal temperature of the battery 10 is the same as the external temperature outside the battery 10 (temperature determination unit). The external temperature is preferably a temperature detected by a temperature sensor installed on the outside (outer surface of the frame) of the battery 10 or a temperature sensor installed in an environment where the battery 10 is installed. For example, when the battery 10 is not used and is left for a long time, the internal temperature of the battery 10 is the same as the external temperature, and step S21 is affirmative. If step S21 is affirmative, the process proceeds to step S22.

[0064] In step S22, the dielectric constant of the battery 10 is calculated using the AC impedance method as described above. Next, in step S23, the dielectric constant of the battery 10 is calculated using the AC impedance method. Figure 6 The internal temperature of the battery 10 is estimated based on the dielectric constant calculated in step S22 according to the relationship shown in (c).

[0065] Then, in step S24, the current external temperature is compared with the estimated internal temperature of the battery 10, and it is determined whether these temperatures are consistent, specifically, whether the difference between these temperatures is within a specified range. Then, if the current external temperature is inconsistent with the estimated internal temperature of the battery 10, the process proceeds to step S25 to calculate the correction factor. Figure 6 This correction value is calculated as an offset correction value, for example, and is used for the next temperature estimation. Figure 6 The estimated internal temperature is corrected by the correction value estimated by the relationship shown in (c). In addition, the correction value is preferably stored in a backup memory such as EEPROM. In addition, it can also be updated by the correction value Figure 6 The structure of the relationship shown in (c).

[0066] According to the present embodiment described in detail above, in the storage battery 10, a unique correlation between temperature and dielectric constant (or capacitor capacity) can be predetermined within a predetermined temperature range including each Curie temperature by adding a plurality of materials having different Curie temperatures to the spacer 24. And by using this correlation, the internal temperature of the storage battery 10 can be estimated based on the dielectric constant.

[0067] In the structure of this embodiment, when the temperature changes inside the battery, the temperature changes can be directly detected. Therefore, unlike the technology using a temperature sensor outside the battery as the prior art, there is no need to wait for the transfer of heat from the inside of the battery to the outside, and the deviation and time delay of temperature detection can be suppressed.

[0068] For example, when the battery 10 is left for a long time, the internal temperature of the battery 10 is the same as the external temperature. In this case, by comparing the internal temperature (estimated temperature) of the battery 10 with the external temperature, the deviation of the correlation between the temperature and the dielectric constant can be grasped. In view of this, based on the temperature comparison as described above, a correction value for correcting the correlation is calculated, so that the accuracy of the temperature estimation in the battery 10 can be improved.

[0069] In the storage battery 10, wiring is usually connected at the positive terminal 14 and the negative terminal 15, and in this state, the voltage between the terminals and the current flowing are appropriately measured. In view of this, by applying the existing measurement function, the dielectric constant or capacitor capacity of the storage battery 10 can be easily calculated. That is, the temperature inside the battery can be appropriately estimated while using the existing structure.

[0070] Incidentally, in the case where a battery module is constituted by a plurality of storage batteries 10 (in other words, in the case where a battery pack is constituted by a plurality of battery cells as the storage batteries 10), a function of measuring the voltage between the terminals or the current flowing is provided for each storage battery 10. In this case, since the dielectric constant or the capacitor capacity of all the storage batteries 10 can be calculated in the battery module, the voltage detection, the current detection, and the internal temperature detection of all the storage batteries (all units) can be realized.

[0071] (Third Embodiment) In the ferroelectric of the spacer 24 added to the battery 10, the relative dielectric constant εr changes according to the temperature change of the battery 10. For example, Figure 8 As shown, it is considered that εr is 1500 when the temperature of the battery 10 is 25°C, and εr is 5000 when the temperature of the battery 10 is 110°C. In this case, when the battery 10 is used, if the relative dielectric constant εr of the ferroelectric of the spacer 24 can be known, the temperature of the battery 10 can be grasped. The temperature range corresponding to εr of the ferroelectric attached to the spacer 24 preferably includes the melting temperature of the spacer 24 or a temperature near its melting temperature. In addition, the dielectric constant ε may be used as a parameter instead of the relative dielectric constant εr.

[0072] In the battery 10, impedance measurement is performed by applying an AC signal with a frequency of about 1 to 10 kHz, for example. At this time, the internal resistance of the battery 10 is calculated from the real part (real part of the zero crossing point) whose imaginary part is 0 in the complex impedance plane curve (Cole-Cole plot) representing the frequency characteristics of the battery 10. The real part of the zero crossing point mainly represents the resistance when the charge in the solution in the battery 10 moves, that is, the solution resistance.

[0073] Here, the author of the present application confirmed that, in the frequency domain (1 to 10 kHz) used when calculating the internal resistance of the storage battery 10, even if the relative dielectric constant εr of the ferroelectric of the spacer 24 is different, there is no difference between the imaginary part and the real part of the impedance. In contrast, in a frequency domain higher than the frequency domain used when calculating the internal resistance, it was confirmed that, when the relative dielectric constant εr of the ferroelectric of the spacer 24 is different, there is a difference between the imaginary part and the real part of the impedance.

[0074] Fig. 9 is a diagram showing an example of a complex impedance plane curve of the battery 10. Fig. 9 In the figure, (a) shows the impedance characteristics when the frequency is changed in the range of 0.1 Hz to 1 MHz, and (b) shows the impedance characteristics of the X part including the vicinity of the zero-crossing point in (a) in an enlarged manner. Fig. 9 Two characteristics are shown when the relative dielectric constant εr is 1500 and 5000.

[0075] exist Fig. 9 (b), that is Fig. 9 In the X part of (a), the impedance characteristics of either εr = 1500 or 5000 are the same, and the real part Re_Z calculated as the zero crossing point is also the same. In addition, the larger the applied frequency, the smaller the real part Re_Z of the impedance becomes. In contrast, Fig. 9 In (a), in a region higher in frequency than the X portion, the impedance characteristics differ between the case of εr=1500 and the case of εr=5000, and the impedance measurement points at each frequency are different.

[0076] according to Fig. 9 (a), as the relationship between the frequency f and the real part Re_Z, it can be derived Fig.10 relationship. Fig.10 In the frequency domain Y, the real part Re_Z is different when εr=1500 and when εr=5000. The frequency domain Y is a frequency domain of 20 to 800 kHz. That is, by applying an AC signal of a predetermined frequency in the frequency domain Y to the storage battery 10, a value corresponding to the relative dielectric constant εr of the ferroelectric in the spacer 24 can be derived as the real part Re_Z of the impedance.

[0077] For example, when an AC signal of a frequency fa (e.g., 40 kHz) in the frequency domain Y is applied to the battery 10, if the relative dielectric constant εr is 1500, the real part Re_Z is A1, and if the relative dielectric constant εr is 5000, the real part Re_Z is A2. In addition, if the relative dielectric constant εr is between 1500 and 5000, the real part Re_Z is an intermediate value between A1 and A2.

[0078] In this embodiment, by Fig.12 The control device 50 shown applies an AC signal having a frequency higher than the AC frequency corresponding to the zero-crossing point in the complex impedance characteristic of the battery 10, calculates the relative dielectric constant εr in the spacer 24 based on the response signal obtained when the AC signal is applied, and monitors the internal temperature of the battery 10 based on the relative dielectric constant εr. In this case, the control device 50 analyzes the voltage fluctuation as the response signal and calculates the real part Re_Z of the impedance. In addition, using Fig.10 The relative dielectric constant εr of the ferroelectric is calculated according to the real part Re_Z, and the battery temperature is monitored based on the relative dielectric constant εr. The control device 50 is composed of a microcomputer having a CPU (computing device) and a storage device (various memories), and various functions are realized by executing programs stored in the storage device.

[0079] In addition, in this embodiment, it is assumed that Fig.11 The structure shown is an equivalent circuit of the battery 10. Fig.11 In the figure, L is the inductance of the winding body 21 including the positive electrode collector 26 and the negative electrode collector 27. R1 is the resistance of the electrolyte, and C1 is the capacitor component of the ferroelectric (barium titanate). These R1 and C1 are connected in parallel. In addition, R2 is the combined resistance of the reaction resistance of the positive electrode active material (resistance during insertion) and the reaction resistance of the negative electrode active material, and C2 is the combined capacitance of the double electric layer formed at the interface between the positive electrode active material and the electrolyte and the double electric layer formed at the interface between the negative electrode and the electrolyte. These R2 and C2 are connected in parallel. Zcpe is the pseudo-capacitance impedance (Constant Phase Element), which is defined by the following formula.

[0080] [Mathematical formula 1] j is the imaginary unit, ω is the angular frequency, p is the CPE index, and T is the CPE constant.

[0081] exist Fig.12 In the embodiment, the control device 50 includes an AC signal applying unit 51, a response signal measuring unit 52, and a battery monitoring unit 53. The AC signal applying unit 51 includes an oscillator that generates an AC signal of a predetermined frequency, and applies the AC signal of the predetermined frequency to the positive and negative sides of the battery 10. In the present embodiment, the AC signal applying unit 51 applies an AC signal of a predetermined frequency in a frequency range of 1 to 10 kHz to the battery 10 when calculating the internal resistance of the battery 10, and applies an AC signal of a predetermined frequency in a frequency range of 20 to 800 kHz to the battery 10 when monitoring the temperature of the battery 10. In the following description, the frequency range of 1 to 10 kHz used in calculating the internal resistance of the battery 10 is referred to as the first frequency range Y1, and the frequency range of 20 to 800 kHz used in monitoring the temperature of the battery 10 is referred to as the second frequency range Y2. The AC signal may be a rectangular wave, a triangular wave, or the like in addition to a sine wave signal.

[0082] The response signal measuring unit 52 measures voltage fluctuations, which are information reflecting the impedance of the battery 10 , as a response signal in a state where an AC signal of a predetermined frequency is applied to the battery 10 by the AC signal applying unit 51 .

[0083] The battery monitoring unit 53 calculates the internal resistance or relative dielectric constant εr of the battery 10 as a battery parameter indicating the state of the battery 10 based on the response signal (voltage change) measured by the response signal measuring unit 52. Specifically, in the battery monitoring unit 53, the resistance calculating unit 53a calculates the real part Re_Z of the impedance as the internal resistance of the battery 10 based on the voltage change measured by the response signal measuring unit 52 and the amplitude of the AC current flowing through the battery 10 when the AC signal is applied, when an AC signal of a predetermined frequency in the first frequency domain Y1 is applied.

[0084] Furthermore, when an AC signal of a predetermined frequency in the second frequency domain Y2 is applied, the dielectric constant calculation unit 53b calculates the real part Re_Z of the impedance based on the voltage change measured by the response signal measurement unit 52 and the amplitude of the AC current flowing through the battery 10 when the AC signal is applied, and calculates the relative dielectric constant εr of the ferroelectric material based on the real part Re_Z. Furthermore, the temperature monitoring unit 53c monitors whether the battery 10 is overheated based on the relative dielectric constant εr.

[0085] Fig.13 2 is a flowchart showing the temperature monitoring process of battery 10 . This process is executed by control device 50 at a predetermined cycle.

[0086] exist Fig.13 In step S21, it is determined whether the implementation condition for currently implementing the temperature monitoring of the battery 10 is satisfied. The implementation condition is a condition for calculating the relative dielectric constant εr of the battery 10, and is preferably a condition that is satisfied at a predetermined period during the running of the vehicle (when the IG is turned on) or after the running of the vehicle stops (after the IG is turned off). The predetermined period is, for example, a period every several seconds, a period every several hundred milliseconds, or a period every several tens of milliseconds.

[0087] If the implementation condition of temperature monitoring is not satisfied, proceed to step S22. In step S22, it is determined whether it is time to calculate impedance. For example, immediately after the IG of the vehicle is turned on, it is assumed that the impedance calculation condition is satisfied and step S22 is affirmative. If step S22 is affirmative, proceed to step S23, and apply an AC signal of a predetermined frequency in the first frequency domain Y1 to the battery 10. Thereafter, in step S24, a voltage change relative to the AC signal is obtained as a response signal, and in the following step S25, the real part Re_Z of the impedance is calculated based on the voltage change as the internal resistance of the battery 10.

[0088] In addition, if step S21 is affirmative, the process proceeds to step S26, and an AC signal of a predetermined frequency in the second frequency domain Y2 is applied to the battery 10. Then, in step S27, a voltage change relative to the AC signal is obtained as a response signal. Next, in step S28, the real part Re_Z of the impedance is calculated based on the voltage change, and the relative dielectric constant εr of the ferroelectric is calculated based on the real part Re_Z. At this time, it is best to predetermine the relationship between the real part Re_Z of the impedance and the relative dielectric constant εr. Fig.14 The relationship shown in FIG. 1 is used to calculate the relative dielectric constant εr of the ferroelectric based on the real part Re_Z.

[0089] Thereafter, in step S29, it is determined whether the relative dielectric constant εr calculated in step S28 is greater than a predetermined threshold value Th. The threshold value Th is determined as a value corresponding to the melting temperature of the spacer 24. According to step S29, it is determined whether the internal temperature of the battery 10 has risen to the melting temperature of the spacer 24 (e.g., 120°C) or a temperature near the melting temperature (e.g., 110°C). At this time, if the relative dielectric constant εr is greater than the threshold value Th, it is considered that the internal temperature of the battery 10 has risen to a temperature equivalent to the melting temperature of the spacer 24, and step S29 is affirmative, and the process proceeds to step S30. In step S30, the user or the like is notified that thermal runaway of the battery 10 may occur.

[0090] According to the third embodiment described above, in addition to the above-mentioned effects, the following effects are also achieved.

[0091] An AC signal having a frequency higher than the AC frequency corresponding to the zero-crossing point in the complex impedance characteristic is applied to the battery 10, and the relative dielectric constant εr of the spacer 24 is calculated based on the response signal obtained in this state. Then, based on the calculated relative dielectric constant εr, the internal temperature of the battery 10 is monitored. In this way, the internal temperature of the battery 10 can be grasped ideally.

[0092] The AC signal applying unit 51 applies an AC signal of a first frequency (a frequency in the first frequency domain Y1) and an AC signal of a second frequency (a frequency in the second frequency domain Y2) higher than the first frequency for measuring complex impedance characteristics near the zero-crossing point. Then, the internal resistance of the battery 10 is calculated based on the response signal of the state in which the AC signal of the first frequency is applied, and the relative dielectric constant εr in the spacer 24 is calculated based on the response signal of the state in which the AC signal of the second frequency is applied. In this case, the calculation of the internal resistance and the calculation of the relative dielectric constant εr can be appropriately performed while distinguishing between the use of an AC frequency suitable for calculating the internal resistance of the battery 10 and an AC frequency suitable for calculating the relative dielectric constant εr of the spacer 24.

[0093] (Other embodiments) For example, the above-described embodiments may be modified as follows.

[0094] The ferroelectric added to the spacer 24 in the storage battery 10 may also be a ferroelectric whose dielectric constant is a maximum value at a predetermined extremely low temperature (e.g., -10°C). In this case, the control device 40 (temperature monitoring unit) determines whether the internal temperature of the storage battery 10 has dropped to an extremely low temperature based on the dielectric constant or the capacitor capacity. Thus, as the usage status of the storage battery 10, the usage frequency in an extremely low temperature state can be monitored.

[0095] In the third embodiment, the frequency of the AC signal is set to 1 to 10 kHz when calculating the internal resistance of the battery 10, and the frequency of the AC signal is set to 20 to 800 kHz when monitoring the temperature of the battery 10, but the frequency can be changed. For example, when monitoring the temperature of the battery 10, the frequency of the AC signal can be higher than when calculating the internal resistance of the battery 10, and it is preferably set to 10 kHz or more.

[0096] When the temperature of the battery 10 is higher than a predetermined temperature lower than the melting temperature of the separator 24, the calculation frequency of the relative dielectric constant εr may be increased compared to when the temperature is lower than the predetermined temperature. Fig.15 processing. Fig.15 Yes Fig.13 In a figure in which a part of the flowchart is changed, the same step number is attached to the same processing.

[0097] exist Fig.15 In step S28, the relative dielectric constant εr of the ferroelectric is calculated based on the voltage change in response to the AC signal. Thereafter, in step S31, it is determined whether the relative dielectric constant εr calculated in step S28 is greater than a specified first threshold value Th1. The first threshold value Th1 is determined as a value corresponding to a specified temperature (for example, 70°C) lower than the melting temperature (120°C) of the spacer 24. In addition, the first threshold value Th1 is preferably the upper limit temperature of the battery 10 during normal use or a temperature higher than its upper limit temperature. At this time, if the relative dielectric constant εr is below the first threshold value Th1, the present processing is temporarily terminated. If the relative dielectric constant εr is greater than the first threshold value Th1, the process proceeds to step S32.

[0098] In step S32, it is determined that the frequency of calculating the relative dielectric constant εr is greater than that in the normal case (i.e., when εr≤Th1) in the next temperature monitoring process. For example, it is preferable to set the frequency of calculating the relative dielectric constant εr to n times (n is greater than 2) the frequency in the normal case. Thus, in the next temperature monitoring process, the frequency of calculating the relative dielectric constant εr is increased with the affirmative determination of step S21.

[0099] Thereafter, in step S33, it is determined whether the relative dielectric constant εr is greater than a predetermined second threshold value Th2. The second threshold value Th2 is a value greater than the first threshold value Th1 and is determined to correspond to the melting temperature of the spacer 24. If the relative dielectric constant εr is greater than the second threshold value Th2, it is considered that the internal temperature of the battery 10 has risen to a temperature equivalent to the melting temperature of the spacer 24, and the process proceeds to step S34. In step S34, a user or the like is notified that thermal runaway of the battery 10 may occur.

[0100] According to the above configuration, in a normal state of battery 10 , the calculation frequency of relative dielectric constant εr is relatively low, which can reduce the calculation load and power consumption, and can temporarily improve the detection sensitivity of temperature rise when thermal runaway may occur.

[0101] As ferroelectrics, lead titanate, potassium niobate, lithium niobate, lead niobate, barium strontium niobate, lithium tantalate, potassium sodium tartrate (Rochelle salt), potassium dihydrogen phosphate, glycine trisulfide, etc. can be used in addition to barium titanate. In addition, as a substance whose dielectric constant changes according to temperature, in addition to ferroelectrics, ordinary dielectrics can be used. For example, ordinary dielectrics such as magnesium titanate, calcium titanate, titanium oxide (particularly rutile type), strontium titanate, forsterite (2MgO·SiO2), and stearite (MgO·SiO2) can be used.

[0102] In the above-mentioned embodiments, the present disclosure is applied to a can-type lithium ion battery, but it can also be applied to a stacked lithium ion battery. In addition, it can also be applied to a nickel-hydrogen battery or the like as a battery other than a lithium ion battery.

[0103] The control unit and the method of the control unit described in the present disclosure may also be implemented by a special-purpose computer, which is provided by constituting a processor and a memory, and the above-mentioned processor is programmed to perform one or more functions embodied by a computer program. Alternatively, the control unit and the method thereof described in the present disclosure may be implemented by a special-purpose computer, which is provided by constituting a processor composed of one or more special-purpose hardware logic circuits. Alternatively, the control unit and the method thereof described in the present disclosure may be implemented by one or more special-purpose computers, which are constituted by a combination of a processor and a memory programmed to perform one or more functions and a processor composed of one or more hardware logic circuits. In addition, the computer program may also be stored in a computer-readable non-temporary tangible recording medium as an instruction executed by a computer.

[0104] Although the present disclosure is described based on the embodiments, it should be understood that the present disclosure is not limited to the above-mentioned embodiments and structures. The present disclosure also includes various modifications and modifications within the equivalent range. In addition, various combinations and methods, and other combinations and methods containing only one element, above or below them, also belong to the scope and thought range of the present disclosure.

[0105] The following describes technical ideas extracted from the above-mentioned embodiments. [Structure 1] A storage battery, The above-mentioned storage battery (10) comprises a positive electrode layer (22), a negative electrode layer (23) and a separator (24) arranged between the positive electrode layer and the negative electrode layer. The spacer is provided in a form containing a substance whose dielectric constant changes according to temperature. [Structure 2] A storage battery as described in Structure 1, wherein: As the above substance, a ferroelectric is used. [Structure 3] A storage battery as described in Structure 1, wherein: The separator melts when the battery reaches a predetermined melting temperature. As the above-mentioned substance, a ferroelectric whose Curie temperature, at which the dielectric constant reaches a maximum value, is at or near the melting temperature of the above-mentioned spacer is used. [Structure 4] A battery cell, comprising: The battery according to any one of structures 1 to 3; a calculation unit (31) which applies an AC signal to the positive electrode layer and the negative electrode layer and calculates a dielectric constant or a capacitor capacity based on the response signal; and A temperature monitoring unit (32) monitors the internal temperature of the battery based on the dielectric constant or capacitor capacity calculated by the calculation unit. [Structure 5] A battery cell as described in Structure 4, wherein: In the above storage battery, the separator melts when the interior of the battery reaches a predetermined melting temperature. As the above-mentioned substance, a ferroelectric having a maximum dielectric constant and a Curie temperature at or near the melting temperature of the above-mentioned spacer is used. The temperature monitoring unit determines whether the internal temperature of the battery has risen to a predetermined temperature determined as a melting temperature of the separator or a temperature in the vicinity thereof, based on the dielectric constant or capacitor capacity calculated by the calculation unit. [Structure 6] A battery cell as described in Structure 4, wherein: In the above storage battery, the above substance includes a plurality of substances having different Curie temperatures at which the dielectric constant reaches a maximum value, and a unique correlation between temperature and dielectric constant or capacitor capacity is determined within a predetermined temperature range including the Curie temperatures of the respective substances. The temperature monitoring unit estimates the internal temperature of the battery based on the dielectric constant or capacitor capacity calculated by the calculation unit using the correlation. [Structure 7] The battery cell as described in Structure 6, comprising: a temperature determination unit that determines whether or not an internal temperature of the battery is the same as an external temperature outside the battery; and A correction value calculation unit calculates a correction value for correcting the correlation by comparing the external temperature under the condition with the internal temperature of the battery estimated by the temperature monitoring unit when it is determined that the temperature of the battery is the same as the external temperature. [Structure 8] A battery monitoring device, the battery monitoring device (40) is suitable for a storage battery (10), The battery comprises a positive electrode layer (22), a negative electrode layer (23) and a separator (24) disposed between the positive electrode layer and the negative electrode layer, wherein the separator is disposed in a form containing a material whose dielectric constant changes according to temperature. The battery monitoring device comprises: a calculation unit (31) which applies an AC signal to the positive electrode layer and the negative electrode layer and calculates a dielectric constant or a capacitor capacity based on the response signal; and A temperature monitoring unit (32) monitors the internal temperature of the battery based on the dielectric constant or capacitor capacity calculated by the calculation unit. [Structure 9] A battery monitoring device, The battery monitoring device (50) is applicable to a storage battery according to any one of structures 1 to 3. The battery monitoring device comprises: an AC signal applying unit that applies an AC signal having a frequency higher than an AC frequency corresponding to a zero-crossing point at which an imaginary part of a complex impedance characteristic of the battery is zero, to the positive electrode layer and the negative electrode layer of the battery; a calculation unit that calculates a dielectric constant in the spacer based on a response signal in a state where an AC signal is applied by the AC signal application unit; and A temperature monitoring unit monitors an internal temperature of the battery based on the dielectric constant calculated by the calculation unit. [Structure 10] A battery monitoring device as described in structure 9, wherein: The AC signal applying unit applies an AC signal in a frequency range of 20 to 800 kHz as the AC signal. [Structure 11] A battery monitoring device as described in structure 9 or 10, wherein: The AC signal applying section applies an AC signal of a first frequency and an AC signal of a second frequency higher than the first frequency for measuring the complex impedance characteristic near the zero-crossing point, respectively. The calculation unit calculates the internal resistance of the battery based on the response signal in a state where the AC signal of the first frequency is applied, and calculates the dielectric constant of the spacer based on the response signal in a state where the AC signal of the second frequency is applied. [Structure 12] A battery monitoring device as described in any one of structures 9 to 11, wherein: In the above storage battery, the separator melts when the interior of the battery reaches a predetermined melting temperature. The calculation unit increases the calculation frequency of the dielectric constant when the temperature of the storage battery is higher than a predetermined temperature lower than the melting temperature, compared with a case where the temperature is lower than the predetermined temperature.

Claims

1. A secondary battery, the secondary battery (10) comprising a positive electrode layer (22), a negative electrode layer (23) and a separator (24) arranged between the positive electrode layer and the negative electrode layer, The spacer is provided in a form containing a substance whose dielectric constant changes according to temperature.

2. The battery according to claim 1, characterized in that As the substance, a ferroelectric is used.

3. The battery according to claim 1, characterized in that The separator melts when the battery interior reaches a predetermined melting temperature. As the substance, a ferroelectric having a maximum dielectric constant and a Curie temperature at or near the melting temperature of the spacer is used.

4. A battery cell, comprising: The battery according to any one of claims 1 to 3; a calculation unit (31) which applies an AC signal to the positive electrode layer and the negative electrode layer and calculates a dielectric constant or a capacitor capacity based on the response signal thereof; as well as A temperature monitoring unit (32) monitors the internal temperature of the battery based on the dielectric constant or capacitor capacity calculated by the calculation unit.

5. The battery cell according to claim 4, characterized in that In the battery, the separator melts when the interior of the battery reaches a predetermined melting temperature. As the substance, a ferroelectric having a maximum dielectric constant and a Curie temperature at or near the melting temperature of the spacer is used. The temperature monitoring unit determines whether the internal temperature of the battery has risen to a predetermined temperature determined as a melting temperature of the separator or a temperature in the vicinity thereof, based on the dielectric constant or capacitor capacity calculated by the calculation unit.

6. The battery cell according to claim 4, characterized in that In the storage battery, the substance includes a plurality of substances having different Curie temperatures at which the dielectric constant reaches a maximum value, and a unique correlation between temperature and dielectric constant or capacitor capacity is determined within a predetermined temperature range including the Curie temperatures of the respective substances. The temperature monitoring unit estimates the internal temperature of the battery based on the dielectric constant or capacitor capacity calculated by the calculation unit using the correlation.

7. The battery cell according to claim 6, wherein: include: a temperature determination unit that determines whether or not an internal temperature of the battery is the same as an external temperature outside the battery; as well as A correction value calculation unit calculates a correction value for correcting the correlation by comparing the external temperature under the condition with the internal temperature of the battery estimated by the temperature monitoring unit when it is determined that the temperature of the battery is the same as the external temperature.

8. A battery monitoring device, the battery monitoring device (40) being applicable to a storage battery (10), the storage battery comprising a positive electrode layer (22), a negative electrode layer (23) and a spacer (24) disposed between the positive electrode layer and the negative electrode layer, the spacer being disposed in a form containing a substance whose dielectric constant changes according to temperature, The battery monitoring device comprises: a calculation unit (31) which applies an AC signal to the positive electrode layer and the negative electrode layer and calculates a dielectric constant or a capacitor capacity based on the response signal thereof; as well as A temperature monitoring unit (32) monitors the internal temperature of the battery based on the dielectric constant or capacitor capacity calculated by the calculation unit.

9. A battery monitoring device, the battery monitoring device (50) being applicable to the storage battery according to any one of claims 1 to 3, The battery monitoring device comprises: an AC signal applying unit that applies an AC signal having a frequency higher than an AC frequency corresponding to a zero-crossing point at which an imaginary part of a complex impedance characteristic of the battery is zero, to the positive electrode layer and the negative electrode layer of the battery; a calculation unit that calculates a dielectric constant in the spacer based on a response signal thereof in a state where an AC signal is applied by the AC signal application unit; and A temperature monitoring unit monitors an internal temperature of the battery based on the dielectric constant calculated by the calculation unit.

10. The battery monitoring device according to claim 9, characterized in that The AC signal applying unit applies an AC signal in a frequency range of 20 to 800 kHz as the AC signal.

11. The battery monitoring device according to claim 9, characterized in that The AC signal applying section applies an AC signal of a first frequency and an AC signal of a second frequency higher than the first frequency for measuring the complex impedance characteristics near the zero-crossing point, respectively. The calculation unit calculates the internal resistance of the battery based on the response signal in the state where the AC signal of the first frequency is applied, and calculates the dielectric constant of the spacer based on the response signal in the state where the AC signal of the second frequency is applied.

12. The battery monitoring device according to claim 9, characterized in that In the battery, the separator melts when the interior of the battery reaches a predetermined melting temperature. The calculation unit increases the calculation frequency of the dielectric constant when the temperature of the battery is higher than a predetermined temperature lower than the melting temperature, compared to when the temperature is lower than the predetermined temperature.

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