JP2013149414A - Heating test apparatus for power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating test apparatus capable of heating respective parts of a power storage device more uniformly than usual.SOLUTION: In a heating test apparatus 1 for a power storage device 20, a magnetic field generation section 12 generates an AC magnetic field included in a frequency range of 50 Hz to 5 kHz and applies it to the power storage device 20 so as to heat the power storage device 20 by induction. A temperature detection section 13 detects a temperature of the power storage device 20. A control section 14 controls the intensity of the AC magnetic field generated by the magnetic field generation part 12 on the basis of the temperature detected by the temperature detection section 13.

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage device heating test apparatus, and more particularly to an apparatus for performing a heating test on a large storage device used in an electric vehicle (EV) and a hybrid electric vehicle (HEV). .

  Lithium ion batteries are increasingly used as an example of power storage devices used in mobile information terminal equipment or EVs and HEVs. Under such circumstances, development according to the use of each battery is actively performed from the viewpoint of large capacity, light weight, or large size.

  In addition to the above technical problems, there are also technical problems in terms of thermal stability. Specifically, it is necessary to conduct an evaluation test on the thermal stability of the electricity storage device against the exothermic action due to the rapid chemical reaction of the electricity storage device.

  In the current thermal stability test of an electricity storage device, a test corresponding to an erroneous use test in which an overcharge or short circuit is intentionally made or an actual electricity storage device is directly heated is performed. In the latter heating test, information such as the presence or absence of runaway, the heat generation process of the electricity storage device, and the degree of contribution of the constituent materials to it is extracted. If more detailed information is extracted, the thermal stability of the electricity storage device can be more appropriately evaluated. For this purpose, it is necessary to uniformly heat and heat each part of the electricity storage device at a predetermined temperature increase rate.

  As a conventional method for heating an electricity storage device, several physical thermal energy supply means can be cited. The first method is forced hot air heating using high-temperature air for heat supply. The second method is heater heating using an electric heater. The third method is a method of heating the outer surface of the electricity storage device by induction heating (IH: Induction Heating). The third method is used in an electromagnetic cooker, and performs induction heating using an alternating magnetic field generated based on a high-frequency signal current of 20 kHz to 50 KHz.

  For example, Japanese Unexamined Patent Application Publication No. 2007-244050 (Patent Document 1) describes the first to third methods. Japanese Patent Laying-Open No. 2010-160932 (Patent Document 2) describes a technique for heating a battery container or a tray on which a battery is placed by IH heating, which is the third method described above. However, the techniques described in these documents heat and raise the temperature of the battery in order to suppress a decrease in battery performance at low temperatures, and are not intended for a battery heating test.

  Japanese Patent Laying-Open No. 2010-97835 (Patent Document 3) discloses a method for appropriately evaluating the thermal stability of a lithium secondary battery and its constituent materials. Specifically, the separator described in this document is characterized in that it does not block pores at least in the measurement temperature range of thermal analysis.

JP 2007-244050 A JP 2010-160932 A JP 2010-97835 A

  In a general thermal stability test, controllability of a predetermined temperature increase rate and high temperature holding characteristics after temperature increase are required. However, in the case of a large power storage device, it is difficult to uniformly heat each part of the device. In particular, in the heating by the first to third methods described above, the container that is the outermost surface of the power storage device body to be heated is first heated, and the thermal energy given to this container is conducted from the container toward the deep part. As a result, the structural members inside the electricity storage device are sequentially heated. Since the thermal circuit model in this case is expressed by high-order lag characteristics, in the case of a large-sized power storage device, the temperature difference between the inside of the power storage device and the container at the time of temperature rise may be several tens of degrees.

  Even when feedback control is performed so that the temperature after the temperature rise is maintained at a predetermined target temperature, the conventional technique has problems in terms of temperature stability and controllability. When the internal temperature of the electricity storage device is monitored and controlled to be equal to the target temperature, stable thermal control is difficult due to high-order delay thermal characteristics. When the surface temperature of the power storage device is monitored and controlled so as to be equal to the target temperature, the temperature inside the power storage device will change at a lower temperature than the surface temperature of the power storage device.

  An object of the present invention is to provide a heating test apparatus capable of heating each part of an electricity storage device more uniformly than in the past.

  In one aspect, the present invention is a heating test apparatus for an electricity storage device, and includes a first magnetic field generation unit, a temperature detection unit, and a control unit. The first magnetic field generation unit generates an alternating magnetic field included in a first frequency region of 50 Hz to 5 kHz and applies it to the power storage device in order to perform induction heating on the power storage device. The temperature detection unit detects the temperature of the power storage device. The control unit controls the intensity of the alternating magnetic field generated by the first magnetic field generation unit based on the temperature detected by the temperature detection unit.

  According to the present invention, induction heating is performed by applying an AC magnetic field having a lower frequency than the conventional one included in the frequency range of 50 Hz to 5 kHz to the power storage device, so that each part of the power storage device is heated more uniformly than in the past. Can do.

It is a figure which shows typically the structure of the heat test apparatus 1 by Embodiment 1 of this invention. It is the figure which looked at the heating test apparatus 1 of FIG. 1 from the winding axis direction of the coil 10. FIG. It is a figure for demonstrating the general structure of a secondary battery. It is a figure for demonstrating the structure of the secondary battery 20 shown in FIG. It is a figure which shows an example of the impedance characteristic between the positive electrode of a secondary battery, and the terminal of a negative electrode. FIG. 6 is a diagram for describing an application direction of an alternating magnetic field in the case of the first embodiment. It is a figure for demonstrating the main structural material of a secondary battery. It is a figure which shows the penetration depth of the main structural material of a secondary battery. It is a figure which shows the relationship between the penetration depth (delta) and the frequency f. It is a figure which shows the relationship between the figure of merit (FOM) showing the heating efficiency of a secondary battery, and the frequency f. It is a control block diagram of the heating test apparatus 1 of FIG. 2 is a diagram showing a thermal circuit model of the secondary battery 20 during heating by the heating test apparatus 1. FIG. It is a figure which shows the relationship between the raise temperature of the secondary battery 20 at the time of the heating by the heat test apparatus 1, and elapsed time. FIG. 3 is a diagram showing a temperature distribution of the secondary battery 20 during heating by the heating test apparatus 1. It is a control block diagram of the heating test apparatus 901 of a comparative example. It is a figure which shows the thermal circuit model of the secondary battery 20 at the time of the heating by the heating test apparatus 901. It is a figure which shows the relationship between the raise temperature of the secondary battery 20 at the time of the heating by the heat test apparatus 901, and elapsed time. It is a figure which shows the temperature distribution of the secondary battery 20 at the time of the heating by the heat test apparatus 901. It is a figure which shows typically the structure of the heating test apparatus 2 by Embodiment 3 of this invention. It is the figure which looked at the heating test apparatus 2 of FIG. 19 from the winding axis direction of the coil 10. FIG. 10 is a diagram for explaining an application direction of an alternating magnetic field in the case of the second embodiment. It is a figure which shows typically the structure of the heat test apparatus 3 by Embodiment 4 of this invention. It is a figure which shows an example of a structure of the planar coils 15A and 15B of FIG. It is a figure which shows the other structural example of the planar coils 15A and 15B of FIG. It is a figure which shows typically the structure of the heat test apparatus 4 by Embodiment 5 of this invention. FIG. 10 is a diagram for describing an application direction of an alternating magnetic field in the case of the fourth embodiment. It is a figure which shows the modification of heating part 12A, 12B of FIG. It is a figure which shows the other modification of heating part 12A, 12B of FIG. It is a figure which shows the temperature distribution in the low frequency IH heating with respect to a homogeneous material. It is a figure which shows the time change of the temperature in each position in the low frequency IH heating with respect to a homogeneous material. It is a figure which shows the temperature distribution in the high frequency IH heating with respect to a large sized secondary battery. It is a figure which shows the time change of the temperature in each position in the high frequency IH heating with respect to a large sized secondary battery. It is a figure which shows the temperature distribution in the low frequency IH heating with respect to a large sized secondary battery. It is a figure which shows the time change of the temperature in each position in the low frequency IH heating with respect to a large sized secondary battery. It is a figure which shows the temperature distribution in the 2 frequency IH heating with respect to a large sized secondary battery. It is a figure which shows the time change of the temperature in each position in the 2 frequency IH heating with respect to a large sized secondary battery. It is a figure which shows the temperature distribution in the local IH heating with respect to a large sized secondary battery. It is a figure which shows the time change of the temperature in each position in the local IH heating with respect to a large sized secondary battery.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

[Embodiment 1]
(Overall configuration of heating test apparatus 1)
FIG. 1 is a diagram schematically showing a configuration of a heating test apparatus 1 according to Embodiment 1 of the present invention.

  FIG. 2 is a view of the heating test apparatus 1 of FIG. 1 as viewed from the winding axis direction of the coil 10. With reference to FIG. 1 and FIG. 2, the heating test apparatus 1 performs induction heating on the secondary battery 20 in order to evaluate the thermal stability of the large-sized secondary battery 20 as an electricity storage device used for EV or HEV. It is for heating. The heating test apparatus 1 includes a coil 10, an AC power supply unit 11, a temperature measurement unit 13, and a control unit 14.

  The coil 10 is large in size so that the secondary battery 20 can be arranged inside the coil so that the inside of the secondary battery 20 can be heated at a uniform temperature. A magnetic field in substantially the same direction is applied to the secondary battery 20. 1 and 2, coordinate axes X, Y, and Z are determined so that the direction of the winding axis of the coil 10 is the X direction (note that capital letters X, Y, and Z are used).

  The AC power supply unit 11 causes the coil 10 to generate an AC magnetic field (induction magnetic field) by flowing an AC current through the coil 10. An eddy current is generated in the secondary battery 20 due to electromagnetic induction by the alternating magnetic field, and the secondary battery 20 generates heat due to a resistance loss of the eddy current. The coil 10 and the AC power supply unit 11 constitute a heating unit (low frequency magnetic field generator) 12 that heats the secondary battery 20 by induction heating.

  Here, the frequency of the alternating magnetic field generated by the heating unit 12 is included in the frequency region of 50 Hz to 5 kHz. This frequency region is a frequency lower than the frequency region (20 kHz to 50 kHz) of a conventional AC magnetic field for induction heating used for an electromagnetic cooker or the like. In this specification, for convenience, 50 Hz to 5 kHz is referred to as a low frequency region, and 20 kHz to 50 kHz is referred to as a high frequency region. Induction heating by an alternating magnetic field in a low frequency region is referred to as low frequency induction heating, and induction heating by an alternating magnetic field in a high frequency region is referred to as high frequency induction heating (outer surface induction heating).

  In the case of induction heating by an alternating magnetic field in a high frequency region, if the secondary battery 20 is stored in a metal container, the energy of the alternating magnetic field is all absorbed by the metal container of the secondary battery 20, and the magnetic flux is stored in the container. Does not pass through. On the other hand, in induction heating using an alternating magnetic field in a low frequency region, the energy of the alternating magnetic field is transmitted through the metal container, so that absorption of the magnetic field energy in the container is suppressed, and the inside (the positive electrode plate 31 and the negative electrode in FIG. 3) is suppressed. The absorption of magnetic field energy in the plate 32) increases. As a result, the secondary battery 20 can be heated more uniformly.

  The temperature measurement unit 13 measures the temperature of the secondary battery 20 using a temperature sensor (for example, a thermocouple). Although the temperature detection location is not particularly limited, as shown in FIG. 1, the positive electrode terminal 23P or the negative electrode terminal 23N (referred to as the electrode terminal 23 when collectively referred to) attached to the container 25 of the secondary battery 20 is used. It is desirable to detect temperature. This is because the temperature of the electrode terminal 23 faithfully reflects the temperature inside the secondary battery 20 (the positive electrode plate 31 and the negative electrode plate 32 in FIG. 3) rather than the temperature of the metal container 25.

  The control unit 14 controls the intensity of the alternating current generated by the alternating current power supply unit 11 based on the temperature detection result of the secondary battery 20 by the temperature measurement unit 13.

(Structure of secondary battery)
FIG. 3 is a diagram for explaining a general structure of a secondary battery. 3A shows a winding structure, FIG. 3B shows a flat winding structure, and FIG. 3C shows a stacked structure.

  The secondary battery having a wound structure shown in FIG. 3A includes an electrode stack 21 </ b> A composed of a positive electrode plate 31, a negative electrode plate 32, and a separator 33. In the secondary battery having this structure, the positive electrode plate 31 and the negative electrode plate 32 are wound in a state where they are stacked with the separator 33 interposed therebetween. 3A and 3B, the coordinate axes x, y, and z are determined so that the direction of the winding axis 30 is the x direction (note that lowercase codes x, y, and z are used). The separator 33 maintains the ionic conduction by holding the electrolytic solution, and prevents an electrical short circuit between the positive electrode plate 31 and the negative electrode plate 32. 3A and 3B, the positive electrode plate 31, the negative electrode plate 32, and a part of the separator 33 are shown in a developed manner for easy illustration.

  For example, in a lithium ion secondary battery, the positive electrode plate 31 has a positive electrode active material (for example, lithium cobaltate, lithium nickelate, lithium manganate, etc.) applied to the surface of a strip-shaped aluminum foil serving as a current collector base material. Is. The negative electrode plate 32 is obtained by applying a negative electrode active material (for example, graphite) to the surface of a strip-shaped copper foil that serves as a current collector base material. The separator has a structure of a fine porous film, and is formed of polyethylene or polypropylene.

  The secondary battery having a flat wound structure shown in FIG. 3B also includes an electrode laminate 21 </ b> B composed of a positive electrode plate 31, a negative electrode plate 32, and a separator 33. However, in the secondary battery having this structure, the positive electrode plate 31 and the negative electrode plate 32 are wound in a flat shape in a state where they are overlapped via the separator 33.

  A secondary battery having a stacked structure shown in FIG. 3C includes an electrode stack 21 </ b> C configured by a plurality of positive plates 31, a plurality of negative plates 32, and a plurality of separators 33. In the secondary battery having this structure, the positive plates 31 and the negative plates 32 are alternately stacked via the separators 33. In FIG. 3C, the coordinate axes x, y, and z are determined so that the stacking direction is the x direction (note that lowercase codes x, y, and z are used).

  FIG. 4 is a view for explaining the structure of the large-sized secondary battery 20 shown in FIG. 4A shows the appearance of the secondary battery 20, FIG. 4B shows the internal structure of the secondary battery 20, and FIG. 4C shows the cross-sectional structure of the secondary battery 20. Note that FIG. 4 shows the case where the secondary battery 20 has the flat winding structure of FIG.

  4A to 4C, the secondary battery 20 includes the electrode laminate 21B, the metal container 25, and the electrode terminals 23 (the positive terminal 23P and the negative terminal 23N) described with reference to FIGS. ) Current collector end portions 22P, 22N (positive electrode end portion 22P, negative electrode end portion 22N), and lead wires 24P connecting these current collector end portions 22P, 22N and electrode terminals 23P, 23N, respectively. , 24N.

  Current collector end portions 22P and 22N are provided at both ends in the winding axis direction (x direction) of electrode laminate 21B. The current collector end 22P is electrically connected to the positive electrode plate 31 (see FIG. 3B) constituting the electrode laminate 21B at a plurality of locations. The current collector end 22N is connected to the negative electrode plate 32 (see FIG. 3B) constituting the electrode laminate 21B at a plurality of locations.

  Also in the case where the large-sized secondary battery 20 has the stacked structure described with reference to FIG. 3C, the large-sized secondary battery 20 has the same configuration as that illustrated in FIGS. In this case, the current collector end portions 22P and 22N are provided at both ends in the direction (x direction) perpendicular to the stacking direction of the electrode stack 21C. The current collector end 22P is electrically connected to a plurality of positive plates 31 (see FIG. 3C) constituting the electrode laminate 21C. The current collector end 22N is connected to a plurality of negative plates 32 (see FIG. 3C) constituting the electrode laminate 21C.

(Inductive magnetic field application direction)
There are two directions in which the induction magnetic field is applied to the secondary battery 20. Hereinafter, the application direction of the magnetic field will be described with reference to FIGS.

  The first application direction is a direction (y direction) orthogonal to the positive electrode plate 31 and the negative electrode plate 32 constituting the electrode laminate (21A, 21B, or 21C). In this specification, the magnetic flux in this direction is denoted as φL. In the case of the winding structure shown in FIG. 3A and the flat winding structure shown in FIG. 3B, the direction of the magnetic flux φL is a direction perpendicular to the winding shaft 30 (y direction). In particular, in the case of the flat wound structure of FIG. 3B, it is desirable to apply the induction magnetic field in a direction perpendicular to the flat portion on the side surface of the electrode laminate 21B. In the case of the stacked structure shown in FIG. 3C, the direction of the magnetic flux φL is the stacking direction (y direction) of the electrode stack 21C.

  The second application direction is a direction (x direction) parallel to the positive electrode plate 31 and the negative electrode plate 32 constituting the electrode laminate (21A, 21B, or 21C). In this specification, the magnetic flux in this direction is denoted as ΦR. In the case of the winding structure shown in FIG. 3A and the flat winding structure shown in FIG. 3B, the direction of the magnetic flux φR is a direction parallel to the winding shaft 30 (x direction). In the case of the stacked structure shown in FIG. 3C, the direction of the magnetic flux φR is a direction (x direction) perpendicular to the stacking direction of the electrode stack 21C.

(Difference in heating mechanism depending on the direction of induction magnetic field application)
In the case of induction heating of a large secondary battery, the following heat generation mechanism can be considered.

(i) Heat generation due to eddy current in the metal container when the container of the secondary battery is metal
(ii) Heat generation due to eddy currents in the current collectors constituting the positive and negative plates of the secondary battery
(iii) Heat generation due to current flowing through the electrolyte between the electrodes FIG. 5 is a diagram illustrating an example of impedance characteristics between the positive and negative terminals of the secondary battery. The horizontal axis in FIG. 5 indicates the real part of the impedance, and the vertical axis indicates the imaginary part. As shown in FIG. 5, the electrolyte has a low impedance so that an interelectrode current that is a precondition for induction heating can flow. Therefore, the heat generation mechanism (iii) cannot be ignored.

  Next, based on the heat generation mechanisms (i) to (iii), the difference in the heating mechanism depending on the direction in which the induction magnetic field is applied will be described. First, the case of φL irradiation (a direction perpendicular to the winding axis or a stacking direction) will be described. In the case of a wound structure (FIG. 3A), heat is generated by any of the mechanisms (i) to (iii). In the flat wound structure (FIG. 3B), when an AC magnetic field is applied in a direction perpendicular to the substantially flat side surface, heat is generated mainly by the mechanisms (i) and (ii) described above. In the case of a stacked structure (FIG. 3C), heat is generated mainly by the mechanisms (i) and (ii) described above.

  On the other hand, in the case of φR irradiation (a direction parallel to the winding axis or a direction perpendicular to the stacking direction), heat is generated by any of the mechanisms (i) to (iii). In particular, in the case of a large secondary battery used for EV or HEV, in addition to the above (i) and (ii), magnetic field energy is intensively absorbed by the current collector end portions 22P and 22N in FIG. An exotherm occurs.

  FIG. 6 is a diagram for explaining the application direction of the alternating magnetic field in the case of the first embodiment. In the first embodiment, an alternating magnetic field is applied in a direction orthogonal to the positive electrode plate 31 and the negative electrode plate 32 constituting the secondary battery 20. That is, as shown in FIG. 6, the secondary battery 20 is irradiated with the magnetic flux φL. The direction of the magnetic flux φL is the direction perpendicular to the winding axis when the secondary battery 20 is a winding type or a flat winding type, and the stacking direction when the secondary battery 20 is a stacked type.

(Selecting the frequency of the induction magnetic field)
In order to perform efficient induction heating on the secondary battery, it is necessary to pay attention to the following two points. First, it is necessary to select an appropriate magnetic flux frequency in order for the induced magnetic flux to pass through the secondary battery container and efficiently heat the inside. Secondly, in order to cause an effective heat generation action inside the secondary battery, the positive electrode plate and the negative electrode plate constituting the electrode laminate are urged so as to promote the generation of eddy current with respect to the transmission of the incident magnetic flux. It is necessary to apply a magnetic field so as to be orthogonal. Generally, the amount of heat generated inside a secondary battery is
Calorific value = Eddy current value × Surface resistance value of structural member × cos θ (1)
Given in. Here, θ is an interlinkage angle between the external magnetic flux and the structural member surface.

  In the heating test apparatus 1 according to the first embodiment, by utilizing the highly transmissive characteristics of the low-frequency magnetic field (50 Hz to 5 kHz), heat generation in the secondary battery container is suppressed, and magnetic energy is stored in the secondary battery. It aims to apply uniformly to the structural member. Since the conventional cooking IH is intended to heat cooking container materials (such as cooking pots), a high-frequency magnetic field (20 kHz to 50 kHz) that can absorb magnetic energy on the surface of the container is used. On the other hand, in the case of the heating test apparatus 1, a low frequency magnetic field (50 Hz to 5 kHz) is used in order to suppress the heat generation of the metal container 25 and effectively heat the inside of the secondary battery. Hereinafter, the interaction between the external magnetic flux and the constituent members of the secondary battery will be further described.

  FIG. 7 is a diagram for explaining main constituent materials of the secondary battery. FIG. 7 shows a case where the secondary battery 20 is a lithium ion secondary battery. As shown in FIG. 7, the container of the secondary battery is made of stainless steel (SUS) and has a thickness of 1 to 1.5 mm. An aluminum foil is used for the current collector of the positive electrode, and the thickness thereof is about 50 μm. Copper foil is used for the current collector of the negative electrode, and the thickness thereof is about 50 μm. Since the positive and negative electrode current collectors are wound about 50 to 100 times, the number N of stacked layers of each current collector is about 100 to 200.

FIG. 8 is a diagram showing the penetration depth of the main constituent material of the secondary battery.
Referring to FIG. 8, in order to efficiently interact with an external magnetic field inside the secondary battery, the external magnetic field must penetrate into the inside. The ability to transmit an external magnetic field can be indicated by the penetration depth of the induced current. Due to the eddy current generated by the alternating magnetic field penetrating inside, the inside of the secondary battery generates heat.

  The penetration depth of the eddy current is determined by the interaction between the induced magnetic flux and the metal material. This is called the skin effect, and the eddy current increases as it approaches the surface of the object to be heated and decreases exponentially toward the inside. The penetration depth δ corresponds to the depth when the eddy current is reduced to 0.368 times the surface current density.

  The metal container provided in the secondary battery generates an eddy current in the interlinkage surface of the external magnetic flux and acts to prevent the magnetic flux from penetrating with self-heating. This permeation blocking force increases as the magnetic field frequency increases. The SUS material having a thickness of 1 mm blocks magnetic flux having a frequency of 2 kHz to 30 kHz, and magnetic field energy is converted into thermal energy. On the other hand, in the case of a low frequency magnetic flux of several tens of Hz to 1 kHz, it passes through the metal container (reference numeral 25 in FIG. 4) and penetrates into the electrode laminate (reference numeral 21B in FIG. 4) inside the secondary battery. As a result, the heat generation of the metal container is reduced, and instead, the magnetic field energy is converted into thermal energy in the electrode stack inside the secondary battery.

  The thickness of the current collector single layer is about 50 μm, which is thinner than the penetration depth. However, since the thickness of all laminated layers corresponds to the penetration depth, the electrode laminate absorbs an alternating magnetic field. be able to.

  FIG. 9 is a diagram showing the relationship between the penetration depth δ and the frequency f. The graph of FIG. 9 is a rewrite of the table shown in FIG. In the figure, the thickness of the metal container and the total thickness of the electrode current collector layer are shown together.

When the thickness of the metal container is τc and the penetration depth of the metal container is δc, the transmittance T1 through which the alternating magnetic field passes through the metal container is
T1 = exp (−τc / δc) (2)
It is represented by When the thickness of all layers of the electrode current collector is τe, and the penetration depth of the electrode current collector is δe, the transmittance T2 through which the alternating magnetic field passes through all layers of the electrode current collector is
T2 = exp (−τe / δe) (3)
It is represented by If the figure-of-merit (FOM) of induction heating is defined as the product of the container transmittance and the absorption rate inside the secondary battery, FOM is
FOM = T1 × (1-T2)
= Exp (−τc / δc) × [1-exp (−τe / δe)] (4)
It is expressed as

  FIG. 10 is a diagram showing the relationship between the performance index (FOM) representing the heating efficiency of the secondary battery and the frequency f. As shown in FIG. 10, when f = 500 Hz, the FOM is maximized and the optimum frequency condition is obtained. If a frequency range satisfying FOM> 0.5 is selected, a frequency range of 50 Hz to 5 kHz is obtained. The lower limit frequency of 50 Hz is also a practical limit of induction heating.

  As described above, 50 Hz to 5 kHz is selected as a frequency range that achieves both the condition that the absorption of the AC magnetic field in the secondary battery container is small and the condition that the AC magnetic field is sufficiently absorbed inside the secondary battery. be able to. The optimum frequency within the range of 50 Hz to 5 KHz can be calculated from structural analysis such as the material, size, and shape of the secondary battery, or can be obtained experimentally.

(Effect of Embodiment 1)
Next, a specific effect of the heating test apparatus 1 having the above configuration will be described.

  FIG. 11 is a control block diagram of the heating test apparatus 1 of FIG. The heating test apparatus 1 includes a heating unit (low frequency magnetic field generator) 12 that applies thermal energy Q to the secondary battery 20 to be subjected to the heating test, a temperature measuring unit 13 that measures the temperature T of the secondary battery 20, and a temperature. And a control unit 14 that controls the amount of heat Q output from the heating unit 12 based on the measurement result of the measurement unit 13 (for example, by feedback control). When the start signal ST is given from the outside, the control unit 14 starts to raise the temperature of the secondary battery ST.

  In general, when heating an electricity storage device, it is known that self-heating occurs in addition to heat input from the outside. However, since this self-heating effect can be regarded as a disturbance, the control block diagram of FIG. 11 treats a power storage device such as a deactivated simulated power storage device as having no self-heating effect.

  FIG. 12 is a diagram illustrating a thermal circuit model of the secondary battery 20 during heating by the heating test apparatus 1. The thermal circuit model shown in FIG. 12 shows the response of the temperature (T) of the electricity storage device to the external heat input (Q). The figure shows the first-order lag response characteristic indicated by the thermal resistance R and the thermal capacity C, which is a desirable characteristic for the controlled object. For example, when the heat capacity (C) of the electricity storage device is 2000 J / ° C., if an electric energy (Q) of 200 W is applied, the temperature rises to 85 ° C. after 10 minutes at a predetermined heating rate (5 [° C./min]). To reach.

  When the first-order-lag thermal circuit model shown in FIG. 12 is applied to the control block of FIG. 11, the temperature control of the secondary battery 20 is fed back, so that heating control that compensates for the first-order lag characteristics is performed. As a result, when the temperature is raised or kept at a high temperature, there is an effect that a temperature raising speed and high temperature stability with a predetermined accuracy can be ensured.

  FIG. 13 is a diagram showing the relationship between the rising temperature of the secondary battery 20 and the elapsed time during heating by the heating test apparatus 1. The graph of FIG. 13 shows the detection result of the temperature T of the secondary battery 20 when the low frequency induction magnetic field output from the heating unit (low frequency magnetic field generator) 12 of FIG. 11 is increased stepwise. . The graph of FIG. 13 shows a simple response characteristic with a first-order lag.

  FIG. 14 is a diagram showing the temperature distribution of the secondary battery 20 during heating by the heating test apparatus 1. The graph of FIG. 14 plots the exothermic temperature of the container (measurement location 15) in temperature rising, and each site | part (measurement location 1-14) inside a secondary battery for every time passage. As shown in the graph of FIG. 14, it can be seen that the temperature distribution of the electrode laminate (measurement points 1 to 12) inside the secondary battery is within ± 3 ° C. and is uniform.

(Contrast with comparative example)
FIG. 15 is a control block diagram of the heating test apparatus 901 of the comparative example. In the heating test apparatus 901 of FIG. 15, a hot air generator 912 is provided as a heating unit instead of the low frequency magnetic field generator 12 of FIG. 11.

  Conventional hot air heating, heater heating, high-frequency IH outer surface heating, and the like first heat a container for a secondary battery to be heated. The heat energy given to the container is sequentially propagated from the container wall material to the deep part by heat conduction, thereby sequentially heating the inside of the secondary battery.

  FIG. 16 is a diagram illustrating a thermal circuit model of the secondary battery 20 during heating by the heating test apparatus 901. The temperature rise characteristic by the conventional heating method can be expressed by a high-order lag element in which a number of first-order lag heat circuit elements are cascade-connected as shown in FIG. As a result, when the internal temperature of the large secondary battery is a control target, the phase margin during the negative feedback operation is not sufficient and the internal temperature becomes unstable.

  FIG. 17 is a diagram illustrating the relationship between the rising temperature of the secondary battery 20 and the elapsed time during heating by the heating test apparatus 901. Referring to FIG. 17, the temperature rise characteristic of hot air heating shows a high-order time delay characteristic, and it can be seen that the thermal circuit model shown in FIG. 16 is appropriate.

  FIG. 18 is a diagram illustrating a temperature distribution of the secondary battery 20 during heating by the heating test apparatus 901. The graph of FIG. 18 plots the temperature of each point of a secondary battery for every elapsed time. As shown in FIG. 18, the temperature increases from the central portion (measurement location 1) of the secondary battery toward the container (measurement location 14). The temperature difference between each point of the electrode laminate inside the secondary battery is 40 ° C., and the temperature difference between the center of the secondary battery and the container reaches 80 ° C. Thus, in the case of a large secondary battery, the temperature difference between the inside of the secondary battery and the container is several tens of degrees.

  As described above, in the case of the conventional heating method, a high-order time delay characteristic is obtained. Therefore, when the output of the heating unit 912 is controlled based on the measurement result of the temperature inside the secondary battery, the high-order delay is caused. As a result, stable temperature control becomes difficult. On the contrary, when the output of the heating unit 912 is controlled based on the measurement result of the container temperature, when the container is heated at a predetermined temperature increase rate (for example, 5 ± 2 [° C./min]), Since the internal temperature has a low followability, the temperature tends to be lower than the container temperature, and the temperature of the entire secondary battery is not necessarily controlled.

  On the other hand, in the case of the heating test apparatus 1 of the first embodiment, the secondary battery is heated uniformly and at a predetermined temperature increase rate throughout the interior of the secondary battery by using low-frequency induction heating. It becomes possible.

(Summary)
As described above, according to the heating test apparatus 1 of the first embodiment, the secondary battery as the power storage device is arranged inside the induction coil, and the frequency of the alternating current applied to the induction coil is a low frequency region different from the conventional one. (50 Hz to 5 kHz). As a result, the heat generating action inside the secondary battery can be increased compared to the heat generating action in the metal container, and the inside of the secondary battery can be heated uniformly.

  With regard to the arrangement conditions of the heating coil that generates the induction magnetic field and the secondary battery that is irradiated with the generated magnetic field, the external magnetic flux is arranged so that the external magnetic flux is perpendicularly incident on the positive electrode plate and the negative electrode plate constituting the electrode laminate. An eddy current is generated in the plane of the positive electrode plate and the negative electrode plate perpendicular to the magnetic flux. As a result, there is an effect of promoting the heat generation of the electrode laminate. In particular, when the secondary battery has a flat wound structure, thermal energy is selectively given to the flat portion by applying a magnetic field perpendicular to the flat portion of the side surface portion. As a result, there is an effect that uniform heating can be performed over the entire electrode laminate.

  Furthermore, a temperature equivalent to the temperature inside the secondary battery can be detected by detecting the temperature of the electrode terminal (either the positive terminal or the negative terminal) attached to the container of the secondary battery. This is because, with reference to FIG. 4, the temperature of the electrode terminals 23P and 23N is the temperature of the current collector end portions 22P and 22N transmitted by thermal conduction through the lead wires 24P and 24N. This is because the end portions 22P and 22N are in close electrical connection with the positive electrode plate 31 and the negative electrode plate 32 of FIG.

  In the above embodiment, the case where the secondary battery container (housing) is made of metal has been described. However, the case where the secondary battery container is non-metallic is the same as in the case of Embodiment 1. The effect of. That is, the entire secondary battery can be uniformly heated by performing induction heating using an alternating magnetic field in a low frequency region (50 Hz to 5 kHz).

[Embodiment 2]
Even when energy absorption in the container is reduced and uniform thermal energy is applied to the inside of the secondary battery by low frequency induction heating by the heating test apparatus 1 of the first embodiment, the applied thermal energy is stored in the electricity storage device. Thermal diffusion toward the container and outside. This thermal diffusion continues until the temperature inside the secondary battery and the temperature of the container are balanced. As a result, when the magnetic energy irradiated from the outside is constant, the temperature distribution of the secondary battery is a temperature distribution that is higher in the central part inside the secondary battery and lowers toward the peripheral part.

  For example, in the case of FIG. 14 described above, the container temperature at the measurement location 15 is lower than that of the electrode current collector (measurement locations 1 to 12). That is, a temperature decreasing tendency is seen from the inside of the electricity storage device toward the container. If the temperature of the secondary battery is further increased, the temperature difference from the external environment temperature widens, so that the temperature distribution of the secondary battery is expected to increase.

  In the second embodiment, a means for uniforming such a non-uniform temperature distribution is provided. Specifically, the frequency of the induced magnetic field is optimized in consideration of the temperature distribution of the secondary battery. That is, by giving the frequency opt2 shifted to a value higher than the optimum value opt1 of the frequency of the alternating magnetic field described in the first embodiment, the magnetic field energy from the outside contributes to the temperature rise of the electrode current collector, and the container It will also contribute to the temperature rise. For example, the frequency of the alternating magnetic field is set in advance so that the temperature at the center of the electrode stack and the temperature of the container are substantially equal. The optimum frequency that reduces the thermal equilibrium temperature difference in both the container and the internal structure of the secondary battery can be uniquely determined from the 50 Hz to 50 KHz frequency band. As a result, a thermal equilibrium state with a lower temperature gradient inside the electricity storage device can be realized, so that the thermal diffusion effect of each part of the electricity storage device body can be suppressed.

[Embodiment 3]
FIG. 19 is a diagram schematically showing the configuration of the heating test apparatus 2 according to Embodiment 3 of the present invention.

FIG. 20 is a view of the heating test apparatus 2 of FIG. 19 as viewed from the winding axis direction of the coil 10.
FIG. 21 is a diagram for explaining the application direction of the alternating magnetic field in the second embodiment. 19 to 21, the configuration of the heating test apparatus 2 is the same as that of the heating test apparatus 1 of the first embodiment, but the positional relationship between the secondary battery 20 and the coil 10 is the same as that of the first embodiment. Different from the case. In the case of Embodiment 3, a magnetic field is applied in parallel with the positive electrode plate and the negative electrode plate constituting secondary battery 20 (magnetic flux φR in FIG. 21). That is, in the case of a winding type or flat winding type structure, a magnetic field is applied in a direction parallel to the winding axis, and in the case of a laminated type structure, a magnetic field is applied in a direction perpendicular to the stacking direction.

  As a result, heat is generated inside the electrode laminate by eddy current flowing through the electrolyte between the electrodes. In the case of a large-sized secondary battery used for EVs and HEVs, heat generation due to eddy current loss occurs intensively at the current collector end portions 22P and 22N shown in FIG. The absorbed thermal energy generated at the current collector end portions 22P and 22N is given to each part of the electrode laminate 21B by heat conduction. As a result, the temperature inside the secondary battery rises uniformly. Since the other points are the same as in the case of the first embodiment, description thereof will not be repeated.

  As in the case of the first embodiment, by measuring the temperature of the electrode terminals 23P and 23N, a temperature equivalent to the temperature inside the secondary battery 20 can be detected. As described in Embodiment 2, the frequency of the alternating magnetic field to be applied may be set so that the temperature of the container and the temperature inside the secondary battery are uniform.

[Embodiment 4]
(Configuration of heating test apparatus 3)
FIG. 22 is a diagram schematically showing the configuration of the heating test apparatus 3 according to the fourth embodiment of the present invention.

  22 is replaced with the low frequency magnetic field generator 12 comprised by the coil 10 and the alternating current power supply part 11, and the 1st, 2nd comprised by the planar coils 15A and 15B and the alternating current power supply part 11 is shown. 1 and 19 is different from the heating test apparatuses 1 and 2 of FIG. 1 and FIG. The first local magnetic field generator configured by the planar coil 15A generates a local magnetic flux φRX that is applied in a concentrated manner to the current collector end (positive electrode end) 22P. The second local magnetic field generator configured by the planar coil 15B generates a local magnetic flux φRX that is concentrated and applied to the current collector end (negative electrode end) 22N.

  Since the frequency of the magnetic flux φRX is included in the low frequency region of 50 Hz to 5 kHz, the point that heat generation of the container 25 can be suppressed is the same as in the first to third embodiments. However, the point which can selectively heat collector end part 22P and 22N with a local magnetic field differs from the case of Embodiment 1-3. Hereinafter, a configuration example of the planar coils 15A and 15B in FIG. 22 will be described.

FIG. 23 is a diagram illustrating an example of the configuration of the planar coils 15A and 15B in FIG.
FIG. 24 is a diagram illustrating another configuration example of the planar coils 15A and 15B in FIG. Referring to FIGS. 23 and 24, planar coils 15 </ b> A and 15 </ b> B include spiral pattern wirings 41 and 42 formed on insulating substrate 40. In the case of the configuration shown in FIG. 23, the magnetic field can be applied more locally than in the case of the configuration shown in FIG.

(Effect of heating test apparatus 3)
According to the heating test apparatus 3 having the above-described configuration, the planar coils 15A and 15B are arranged so that the current collector ends 22P and 22N of the secondary battery 20 are concentrated and generate heat. The current collector end portions 22P and 22N serve as a primary heat source, and the generated heat is evenly diffused to the electrode layers connected to the current collector end portions. Although each electrode layer has a different thermal characteristic, in such a heat supply circuit from the end of the current collector, the thermal resistance value of each electrode layer is low, so the temperature variation between the electrode layers is small. As a result, the amount of heat generated at the current collector end portions 22P and 22N is simultaneously supplied to each electrode layer through a thermal diffusion process in parallel, so that the temperature and the heating rate of each electrode layer become uniform.

  In the case of conventional forced hot air heating, heater resistance heating, or high-frequency IH outer surface heating, heating is applied to a serial multilayer heat conduction circuit comprising a combination of a dielectric material separator and a metal electrode plate, which is a poor heat conductor. I was doing it. In this case, since the container heating was first preceded, and then the inside of the secondary battery was heated by heat conduction, this temperature-time characteristic was a high-order delay. On the other hand, according to the heating test apparatus 3 of the fourth embodiment, the current collector end portions 22P and 22N which are primary heat sources and the electrode plates to be heated (positive electrode plate, negative electrode plate) are provided. It is close. For this reason, since a number of simple thermal circuits having a first-order lag characteristic are connected in parallel, the temperature-time characteristic becomes a first-order lag. By realizing such a simple first-order lag response, more stable negative feedback heat control becomes possible.

  Furthermore, according to the heating test apparatus 3 of the fourth embodiment, the complex is based on the interaction between the secondary battery 20 (particularly, the internal electrode laminates 21A, 21B, and 21C) that is an aggregate of a plurality of materials and the induction magnetic field. An exothermic process can be avoided. As a result, it is possible to appropriately evaluate the thermal stability even in cases where it is difficult to evaluate the degree of heat generation process and the influence and contribution of each constituent material on it.

  The other points in FIG. 22 are the same as those in FIGS. 1 and 19, and thus the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated. FIG. 22 shows the case where the secondary battery 20 has a flat winding structure, but the heating test apparatus 3 of the fourth embodiment is similarly applied to a secondary battery having a stacked structure. can do. Although two planar coils 15A and 15B are arranged in FIG. 22, a configuration in which only one of them is arranged may be employed.

[Embodiment 5]
FIG. 25 is a diagram schematically showing a configuration of a heating test apparatus 4 according to Embodiment 5 of the present invention.

  The heating test apparatus 4 of FIG. 25 includes a second heating unit 12B configured of an AC power supply unit 11B and a coil 10B in addition to the first heating unit 12A configured of the AC power supply unit 11A and the coil 10A. Thus, it is different from the heating test apparatus 1 of FIG. As described in the first embodiment, the first heating unit 12A applies an AC magnetic field having a frequency f1 optimized so that the electrode stack inside the secondary battery effectively generates heat to the secondary battery. . The second heating unit 12B applies to the secondary battery an alternating magnetic field having a frequency f2 optimized so that the secondary battery container effectively generates heat. The frequency f2 is higher than the low frequency region of 50 Hz to 5 kHz, and is set in the frequency region of 20 kHz to 50 kHz, for example.

  As described above, by the two-frequency induction heating in which alternating magnetic fields having different frequencies are applied simultaneously, the container of the secondary battery and the internal electrode laminate can be simultaneously heated. As a result, the temperature distribution of each part of the secondary battery can be made as uniform as possible. The other points in FIG. 25 are the same as those in FIG. 1, and therefore, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 26 is a diagram for explaining the application direction of the alternating magnetic field in the case of the fourth embodiment. Referring to FIG. 26, the alternating magnetic field is applied in the direction perpendicular to positive electrode plate 31 and negative electrode plate 32 constituting secondary battery 20 in the same manner as described with reference to FIG. That is, the magnetic flux φL1 is applied to the secondary battery 20 by the first heating unit 12A, and the magnetic flux φL2 is applied to the secondary battery 20 by the second heating unit 12B.

  FIG. 27 is a diagram illustrating a modification of the heating units 12A and 12B in FIG. Referring to FIG. 27, when first coil 10A and second coil 10B have a strong coupling relationship, the resulting magnetic field may be weakened as a result of the mutual interference. Therefore, in the modification of FIG. 27, the heating unit 12A further includes a band-pass filter 16A (or a low-pass filter) that allows the current with the frequency f1 to pass therethrough and blocks the current with the frequency f2. The heating unit 12B further includes a band-pass filter 16B (or a high-pass filter) that allows the current with the frequency f2 to pass therethrough and blocks the current with the frequency f1. Thereby, mutual interference between the coils 12A and 12B can be suppressed.

  FIG. 28 is a diagram showing another modification of the heating units 12A and 12B in FIG. In the modification of FIG. 28, the heating unit 12A includes a resonant capacitor 17A and an amplifier 18A connected in parallel with the coil 10A, instead of the AC power supply unit 11A. The heating unit 12B includes a resonance capacitor 17B and an amplifier 18B connected in parallel with the coil 10B, instead of the AC power supply unit 11B.

In each of the heating units 12A and 12B in FIG. 28, assuming that the inductance of the coil is L and the capacitance of the resonant capacitor is C, each heating unit is
f = 1 / [2π × (L × C) ^1/2 ] (5)
It oscillates at the resonance frequency. The amplifier is for sustaining oscillation by supplying electrical energy to compensate for attenuation due to internal resistance.

  The resonance frequency f1 of the heating unit 12A is set to a frequency at which the electrode stack inside the secondary battery effectively generates heat, and the resonance frequency f2 of the heating unit 12B effectively generates heat from the container of the secondary battery. Is set to an optimized frequency. Since the resonance frequencies f1 and f2 are different, mutual interference between the coils 10A and 10B can be suppressed even when the coils 10A and 10B are strongly coupled.

[Thermal analysis results]
Hereinafter, the result of the unsteady thermal analysis calculation using a predetermined battery model will be described.

(Low frequency IH heating for homogeneous materials)
First, the results when the homogeneous material is heated by the low-frequency IH heating described in the first embodiment will be described.

  FIG. 29 is a diagram showing a temperature distribution in low-frequency IH heating for a homogeneous material. As shown in FIG. 29, the temperature distribution of the homogeneous material is not uniform.

  FIG. 30 is a diagram showing the time change of the temperature at each position in the low frequency IH heating for the homogeneous material. As shown in FIG. 30, the first-order lag characteristic is obtained, but the equilibrium temperature after a certain time varies.

(High-frequency IH heating for large secondary batteries)
Next, the result of performing conventional high-frequency IH heating (when the frequency of the AC magnetic field is 20 kHz to 50 kHz) on the large secondary battery will be described.

FIG. 31 is a diagram showing a temperature distribution in high-frequency IH heating for a large secondary battery.
FIG. 32 is a diagram showing a temporal change in temperature at each position in high-frequency IH heating for a large-sized secondary battery. Referring to FIGS. 31 and 32, in the case of high-frequency IH heating in which only the casing (container) of the secondary battery can be heated, variation in the heat generation temperature is recognized during the rising period until a constant thermal equilibrium temperature is reached. This is because the battery is large and reflects the heat diffusion from the previously heated casing. In particular, a delay in response time at positions c and b inside the secondary battery is observed. On the other hand, even if the feedback temperature control is performed, there is a possibility that the control stability may be deteriorated because of the phase delay.

(Low frequency IH heating for large secondary batteries)
Next, the result of performing the low frequency IH heating described in the first embodiment on the large secondary battery will be described.

FIG. 33 is a diagram showing a temperature distribution in low-frequency IH heating for a large secondary battery.
FIG. 34 is a diagram showing a temporal change in temperature at each position in the low-frequency IH heating for the large secondary battery. Referring to FIG. 33, it is shown that an equilibrium state is reached when the battery internal temperature is higher than the ambient temperature, and that there is a temperature gradient from the inside to the outside of the secondary battery. The results shown in FIGS. 33 and 34 are not optimal in terms of uniformity and rise time characteristics. However, as described in the second embodiment, the frequency of the alternating magnetic field is shifted to the high frequency side, or the fifth embodiment. The temperature uniformity can be improved by using the two-frequency IH heating described in the above.

(2-frequency IH heating for large secondary batteries)
Next, the result of performing the two-frequency IH heating described in the fifth embodiment on the large secondary battery will be described.

FIG. 35 is a diagram showing a temperature distribution in two-frequency IH heating for a large-sized secondary battery.
FIG. 36 is a diagram showing a temporal change in temperature at each position in the two-frequency IH heating for the large-sized secondary battery. Compared with the case of the low frequency IH heating shown in FIGS. 33 and 34, in the case of FIGS. 35 and 36, the temperature rise time is shorter, and the temperature distribution after a predetermined time is more uniform. I understand that. That is, when IH heating is performed on a large secondary battery, a more uniform temperature distribution can be obtained by heating both the electrode stack and the container than when intensively heating the electrode stack inside the secondary battery. It is done.

(Local IH heating for large secondary batteries)
Next, the result of performing the local IH heating described in Embodiment 4 on the large secondary battery will be described.

FIG. 37 is a diagram showing a temperature distribution in local IH heating for a large secondary battery.
FIG. 38 is a diagram showing a temporal change in temperature at each position in local IH heating for a large-sized secondary battery. Referring to FIGS. 37 and 38, the heating efficiency is lower than in the case of other IH heating, but there is an advantage that a first order lag characteristic is obtained in the temperature time characteristic. Furthermore, although there are variations in temperature for the first several hundred seconds, there is an advantage that the temperature is stable within 2 to 3 ° C. after thermal equilibrium. In these respects, the results shown in FIGS. 37 and 38 are superior to the results of the high frequency IH heating shown in FIGS.

  The embodiment disclosed this time must be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Heating test apparatus, 10, 10A, 10B coil, 11, 11A, 11B AC power supply part, 12, 12A, 12B Heating part (low frequency magnetic field generator), 13 Temperature measuring part, 14 Control part, 15A, 15B Plane type Coil, 20 secondary battery, 21A, 21B, 21C electrode laminate, 22N current collector end (negative electrode end), 22P current collector end (positive electrode end), 23N electrode terminal (negative electrode terminal), 23P electrode Terminal (positive electrode terminal), 24P, 24N lead wire, 25 container, 30 winding shaft, 31 positive electrode plate, 32 negative electrode plate, 33 separator.

Claims (12)

A first magnetic field generation unit configured to generate a first AC magnetic field included in a first frequency region of 50 Hz to 5 kHz and apply the first AC magnetic field to the power storage device in order to perform induction heating of the power storage device;
A temperature detector for detecting the temperature of the electricity storage device;
An electrical storage device heating test apparatus comprising: a control unit that controls the intensity of the first alternating magnetic field generated by the first magnetic field generation unit based on the temperature detected by the temperature detection unit. The power storage device includes an electrode laminate configured by winding a positive electrode plate and a negative electrode plate via a separator,
The power storage device heating test apparatus according to claim 1, wherein the first magnetic field generation unit applies the first AC magnetic field in a direction perpendicular to a winding axis of the electrode stack. The electricity storage device includes an electrode laminate configured by alternately laminating a plurality of positive plates and a plurality of negative plates one by one through a separator,
The power storage device heating test apparatus according to claim 1, wherein the first magnetic field generation unit applies the first AC magnetic field in a stacking direction of the electrode stack. The electricity storage device further includes a metal container that houses the electrode laminate,
When the transmittance of the first alternating magnetic field passing through the metal container is T1, and the transmittance of the first alternating magnetic field penetrating the electrode stack is T2, the frequency of the first alternating magnetic field is , T1 × (1−T2) is set in advance so as to be larger than a predetermined value.   5. The heating test apparatus for an electricity storage device according to claim 4, wherein the frequency of the first AC magnetic field is set in advance such that T1 × (1−T2) is maximized. The power storage device includes an electrode laminate configured by winding a positive electrode plate and a negative electrode plate via a separator,
The power storage device heating test apparatus according to claim 1, wherein the first magnetic field generation unit applies the first AC magnetic field in a winding axis direction of the electrode stack. The electricity storage device includes an electrode laminate configured by alternately laminating a plurality of positive plates and a plurality of negative plates one by one through a separator,
The power storage device heating test apparatus according to claim 1, wherein the first magnetic field generation unit applies the first AC magnetic field in a direction perpendicular to a stacking direction of the electrode stack. The electricity storage device further includes a metal container that houses the electrode laminate,
The frequency of the first AC magnetic field is set in advance so that the temperature rise in the central portion of the electrode laminate and the temperature rise in the metal container are substantially equal. The heating test apparatus for an electricity storage device according to claim 1. The electricity storage device is:
An electrode laminate configured by winding a positive electrode plate and a negative electrode plate via a separator;
Including a positive electrode end and a negative electrode end respectively provided at both ends of the winding axis direction of the electrode laminate,
The positive electrode end is connected to a positive electrode plate constituting the electrode laminate,
The negative electrode end is connected to a negative electrode plate constituting the electrode laminate,
The first magnetic field generator is concentratedly applied to the first local magnetic field generator and the negative electrode end that generate a local magnetic field that is concentratedly applied to the positive electrode end. The heating test apparatus for an electric storage device according to claim 1, comprising at least one of second local magnetic field generation units that generate a local magnetic field. The electricity storage device is:
An electrode laminate configured by alternately laminating a plurality of positive plates and a plurality of negative plates one by one via a separator;
A positive electrode end and a negative electrode end respectively provided at both ends in a direction perpendicular to the stacking direction of the electrode stack,
The positive electrode end is connected to a plurality of positive electrodes constituting the electrode laminate,
The negative electrode end is connected to a plurality of negative electrodes constituting the electrode laminate,
The first magnetic field generator is concentratedly applied to the first local magnetic field generator and the negative electrode end that generate a local magnetic field that is concentratedly applied to the positive electrode end. The heating test apparatus for an electric storage device according to claim 1, comprising at least one of second local magnetic field generation units that generate a local magnetic field.   The apparatus further comprises a second magnetic field generation unit configured to generate a second AC magnetic field having a frequency higher than the first frequency region and apply the second AC magnetic field to the power storage device to perform induction heating of the power storage device. 2. A heating test apparatus for an electricity storage device according to 1. The electricity storage device is:
A positive electrode plate and a negative electrode plate are wound via a separator, or a plurality of positive electrode plates and a plurality of negative electrode plates are alternately stacked one by one via a separator;
A container for storing the electrode laminate;
A positive electrode terminal attached to the container and electrically connected to one or more positive electrode plates constituting the electrode laminate;
A negative electrode terminal attached to the container and electrically connected to one or more negative electrode plates constituting the electrode laminate,
The power storage device heating test apparatus according to claim 1, wherein the temperature detection unit detects a temperature of the positive electrode terminal or the negative electrode terminal.

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