WO2014148585A1

WO2014148585A1 - Thermal switch, temperature adjustment structure, and battery pack

Info

Publication number: WO2014148585A1
Application number: PCT/JP2014/057627
Authority: WO
Inventors: 拓西垣; 崇弘冨田
Original assignee: 日本碍子株式会社
Priority date: 2013-03-22
Filing date: 2014-03-19
Publication date: 2014-09-25
Also published as: JPWO2014148585A1

Abstract

Provided are a thermal switch with a simple structure capable of changing the heat transfer performance thereof according to temperature, a temperature adjustment structure equipped with the thermal switch, and a battery pack. The thermal switch (1) comprises: a first protective layer (2) which receives heat; a radiation layer (4) which is joined onto the first protective layer (2) and changes emissivity when temperature changes; and a second protective layer (3) which is arranged opposite the radiation layer (4) with a gap (5) formed with the radiation layer (4) and receives heat from the radiation layer (4). The emissivity of the radiation layer (4) changes with change in temperature, so in a thermal switch (1) wherein emissivity increases with a rise in temperature, heat is not liable to be transferred from the first protective layer (2) to the second protective layer (3) when the temperature is low, but is liable to be transferred from the first protective layer (2) to the second protective layer (3) when the temperature is high.

Description

Thermal switch, temperature control structure, and battery pack

∙ It relates to a thermal switch whose heat transfer performance changes depending on the temperature, a temperature adjustment structure provided with the switch, and a battery pack.

In recent years, effective use of thermal energy has been demanded due to CO ₂ emission regulations and energy problems. Heat may or may not be needed. For example, since a battery battery pack mounted on an EV has high resistance when the temperature of the battery is low, heat insulation is required when the temperature is low, and there is concern about ignition due to decomposition of the electrolyte when the temperature is too high. Therefore, heat dissipation is required when the temperature is high. Therefore, it is thought that if there is a technology for controlling the flow of heat, it will lead to effective use of heat.

As such a technique, an element (Patent Document 1) that switches thermal conductivity by applying energy (magnetic field, electric field, light, etc.) to a transition body sandwiched between electrodes, a substrate 1 and a carbon nanotube layer The switch (patent document 2) which switches the connection state which the base material 2 which it has contacts, and the non-connection state which does not contact is disclosed.

International Publication No. 2004/068604 International Publication No. 2012/140927

However, in Patent Document 1, an electrode, wiring, and the like are necessary to switch by applying energy. Moreover, in patent document 2, components other than what itself changes in thermal conductivity are required, and an actuator is provided to change the contact state. Therefore, the switch becomes large and the mounting location is limited from the viewpoint of heat resistance. Moreover, it is difficult to manufacture a complicated shape.

An object of the present invention is to provide a heat switch having a simple structure capable of changing the heat transfer performance depending on the temperature, a temperature adjustment structure including the heat switch, and a battery pack.

The present inventors have found that the above problem can be solved by providing a thermal switch having a radiation layer whose emissivity changes when the temperature changes. That is, according to the present invention, the following thermal switch, a temperature adjustment structure including the same, and a battery pack are provided.

[1] A first protective layer that receives heat, a radiation layer that is bonded onto the first protective layer and changes its emissivity when the temperature changes, and the radiation layer includes a gap between the radiation layer and the radiation layer. And a second protective layer disposed opposite to and receiving heat from the radiation layer.

[2] The thermal switch according to [1], wherein the emissivity of the radiation layer changes by 0.2 or more when the temperature rises or falls.

[3] The thermal switch according to [1] or [2], wherein the radiation layer has an emissivity that changes stepwise.

[4] Any of the above [1] to [3], wherein the radiation layer is formed of any one of an emissivity variable element, a Mott insulator, a metal-semiconductor phase transition material, and a metal-insulator phase transition material. The thermal switch described in.

[5] The thermal switch according to [4], wherein the radiation layer is formed of a perovskite oxide.

[6] The [1] to [5], wherein the first protective layer or the second protective layer is formed of any one selected from the group consisting of oxides, nitrides, ceramics made of carbide, and metals. ] The thermal switch in any one of.

[7] The thermal switch according to any one of [1] to [6], wherein a gap between the radiation layer and the second protective layer is 1 nm or more and 1 mm or less.

[8] The thermal switch according to any one of [1] to [7] is provided around a heat generation source that generates heat, and heat is dissipated between a first temperature and a second temperature that is higher or lower than the first temperature. The temperature adjustment structure which adjusts the temperature by the said heat from the said heat generation source by changing.

[9] A battery pack having the temperature adjustment structure according to [8].

The thermal switch of the present invention operates as a thermal switch having low heat transfer performance at low temperatures and a heat insulation effect, and high heat transfer performance at high temperatures and a heat dissipation effect. Or, conversely, it operates as a heat switch having a high heat transfer performance at a low temperature and a heat dissipation effect, and having a low heat transfer performance and a heat insulation effect at a high temperature.

Also, since the heat transfer performance changes due to changes in ambient temperature, it becomes a self-supporting thermal switch where the heat transfer performance is switched on (high heat transfer performance) or OFF (low heat transfer performance). This eliminates the need for components such as a drive unit, and can reduce the size. In addition, the mountability is high and the degree of freedom in shape is high. A battery pack having a temperature control structure equipped with this thermal switch, for example, a battery pack, can effectively use internal heat and improve its function.

It is a schematic diagram which shows the cross section of a thermal switch. It is a figure which shows the emissivity of a radiation layer. It is a schematic diagram which shows one Embodiment of the formation method of a gap | interval. It is a schematic diagram which shows other embodiment of the formation method of a gap | interval. It is a schematic diagram which shows one Embodiment of the battery pack provided with the thermal switch.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments, and changes, modifications, and improvements can be added without departing from the scope of the invention.

(Thermal switch)
FIG. 1 shows an embodiment of a cross section of the thermal switch 1. The left diagram of FIG. 1 schematically shows the emissivity when the temperature is low, and the right diagram schematically shows the emissivity when the temperature is high. The thermal switch 1 is bonded to the first protective layer 2 for receiving heat, the radiation layer 4 whose emissivity changes when the temperature changes, and the radiation switch 4 and the gap 5. The second protective layer 3 is disposed opposite to the radiation layer 4 and receives heat from the radiation layer 4. Since the emissivity of the radiating layer 4 changes as the temperature changes, the heat switch 1 that increases the emissivity when the temperature rises. When the temperature is low, the heat from the first protective layer 2 is reduced. It is difficult to transmit to the second protective layer 3, and when the temperature is high, heat from the first protective layer 2 is easily transferred to the second protective layer 3. That is, since the emissivity reversibly changes due to a change in ambient temperature, the heat switch 1 changes in heat transferability, that is, heat transfer performance, depending on the temperature. Since the thermal switch 1 does not require parts such as a drive unit, it can be miniaturized. Therefore, it is highly mountable and has a high degree of freedom in shape.

Fig. 2 shows the temperature dependence of the emissivity of the radiation layer 4. As shown in FIG. 2, when the emissivity of the radiation layer 4 changes with temperature, the heat transfer performance of the entire thermal switch 1 changes suddenly and reversibly, and the operation of the thermal switch 1 is switched according to temperature. Functions as a switch. It is preferable that the emissivity of the radiation layer 4 changes stepwise depending on the temperature. The emissivity of the radiation layer 4 is preferably changed by 0.2 or more when the temperature rises (or falls) from the first temperature to the second temperature. That is, the difference between the emissivity at the first temperature immediately before the emissivity increases (or decreases) and the emissivity at the second temperature immediately after the increase (or decreases) is 0.2 or more, more preferably 0.3 or more, Preferably, it varies by 0.4 or more. By changing in this way, the function as a switch can be fully exhibited.

Although 1st temperature and 2nd temperature are not specifically limited, In what has a temperature adjustment structure provided with the thermal switch 1, it has a temperature adjustment structure by changing a heat dissipation state and adjusting temperature. Preferably, the emissivity changes abruptly between the first temperature and the second temperature so that the function of the object can be improved. In order to function as a switch, the temperature difference between the first temperature and the second temperature is preferably small, and the temperature difference is preferably 0.1 to 100 ° C., and preferably 0.1 to 50 ° C. Is more preferable. In the thermal switch 1 whose emissivity increases when the temperature rises, the heat transfer performance of the entire thermal switch 1 is low because the emissivity is low below the first temperature, and it can be said to be in an OFF state. On the other hand, at the second temperature or higher, since the emissivity is high, the heat transfer performance of the entire thermal switch 1 is high, and it can be said to be in an ON state. For example, when the thermal switch 1 is provided on the outer periphery of a battery pack, which will be described later, it is preferable to have the radiation layer 4 having a first temperature of −10 to 20 ° C. and a second temperature of 30 to 60 ° C.

The radiation layer 4 is made of a variable emissivity element, a Mott insulator, a metal-semiconductor phase transition material, a metal-insulator phase transition material, or the like. Those composed mainly of oxides of transition metals and having a perovskite structure are particularly desirable.

As transition metal oxides, ReNiO ₃ (Re is a rare earth element), M1 _{(1- (x + y))} M2 _x M3 _y MnO ₃ (M1 is La, Pr, Sc, In, Nd or Sm, and M2 is alkaline earth) M3 is an alkaline earth metal that is not the same as M2, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1), La _1-xy Sr _x Ca _y MnO ₃ (0 ≦ x ≦ 1, 0 ≦ y) ≦ 1), Ca ₂ Ru _1-x M _x O ₄ (M is Mn or Fe, 0 ≦ x ≦ 1), VO _{2 and the} like.

Transition metal oxides are materials whose emissivity changes at a specific temperature range. Although it is necessary to select the temperature in the temperature region and its temperature range depending on the application, the temperature range is preferably 100 ° C. or less. For example, when used for a battery pack member, the temperature range is preferably 0 ° C. to 50 ° C. Further, it is necessary to select an appropriate change width of the emissivity depending on the application, but the change width of the emissivity is preferably 0.2 or more. For example, when used for a battery pack, it is preferable that the emissivity changes from 0.3 to 0.7, and the change in emissivity is 0.4.

The thickness of the radiation layer 4 is not particularly limited, but is preferably in the range of 10 nm to 10 mm from the viewpoint of ease of manufacture, durability, and cost.

The first protective layer 2 or the second protective layer 3 has a function of protecting the radiation layer 4 from physical damage and chemical damage. Physical damage refers to thermal shock when used where an unsteady thermal history is applied, damage due to sliding when used in an operating part, and the like. Chemical damage refers to corrosion or deterioration when used in the presence of an oxidizing atmosphere or corrosive gas. The first protective layer 2 and the radiation layer 4 are joined, and the radiation layer 4 and the second protection layer 3 are provided with a gap 5. The second protective layer 3 has a role of receiving thermal energy radiated from the radiating layer 4 and releasing it from the opposite surface. The first protective layer 2 or the second protective layer 3 can be formed of metal or ceramics (oxide, nitride, carbide, etc.). Specifically, for example, Al, Ti, Mn, Fe, Ni, Cu, Mo, Ag, W, Au, Pt, and alloys thereof, such as stainless steel, Al ₂ O ₃ , ZrO ₂ , SiO ₂ , Y ₂ O ₃ , sialon, SiC, Si ₃ N ₄ , or AlN. The first protective layer 2 or the second protective layer 3 is preferably a material having high thermal conductivity. The higher the thermal conductivity, the greater the apparent change in thermal conductivity when the switch is OFF and ON.

The radiation layer 4, the second protective layer 3, and the gap 5 are preferably 1 nm or more and 1 mm or less. More preferably, they are 1 nm or more and 100 micrometers or less, More preferably, they are 1 nm or more and 50 micrometers or less. By setting this range, the function as a switch can be exhibited more effectively. The gap 5 is preferably a vacuum, but may be filled with a gas such as air. The method of providing the gap 5 is not particularly limited. For example, as shown in FIGS. 3A and 3B, the layer can be fixed with a heat insulating material 8. Alternatively, a transparent (particularly in the far-infrared to near-infrared region) porous insulating material can be present and fixed in the gap 5. By providing the gap 5, the contribution of conduction heat transfer can be eliminated, radiation heat transfer can be dominant, and the change in heat transfer at the time of switch OFF / ON due to emissivity change can be increased.

(Temperature adjustment structure)
A temperature adjustment structure in which the thermal switch 1 of the present invention is provided around a heat generation source that generates heat will be described. In this specification, the temperature adjustment structure refers to a structure having a function of adjusting temperature while effectively using heat from a heat generation source. The heat generation source that generates heat refers to the one that generates heat, and is not particularly limited. The temperature adjustment structure of the present invention includes a temperature adjustment structure that adjusts the temperature due to the heat of the heat generation source by changing the heat radiation state between the first temperature and the second temperature that is higher or lower than the first temperature. Performance can be improved. Specifically, examples of the heat generation source include a battery pack, a motor, a CPU, a control circuit, an engine, a brake, and a gear box. The structure provided with the thermal switch 1 around these is a temperature adjustment structure. In the case where sunlight is used as the heat generation source, an indoor temperature adjustment structure can be obtained by providing the building material, window, and sash with the thermal switch 1.

FIG. 4 shows an embodiment of the battery pack 30 provided with the thermal switch 1. The battery pack 30 is a heat generation source. The battery pack 30 includes a plurality of batteries, and these are electrically connected and accommodated in the case 31. As shown in FIG. 4, the thermal switch 1 is provided on the outer peripheral portion of the battery pack 30, that is, the case 31.

The battery pack 30 has a high battery resistance because it is at a low temperature when starting. Therefore, it is preferable not to dissipate the heat inside the battery pack 30 as much as possible. On the other hand, after the completion of warming up, if the temperature inside the battery pack 30 is too high, there is a concern of ignition due to decomposition of the electrolyte. Therefore, it is preferable to actively dissipate the heat inside the battery pack 30. As shown in FIG. 4, by providing the thermal switch 1 on the outer periphery of the battery pack 30, it is difficult to dissipate heat at the time of starting, and heat can be used effectively. Moreover, since emissivity becomes high after completion of warm-up, the heat inside the battery pack 30 can be actively dissipated.

(Method for manufacturing thermal switch)
When the first protective layer 2 and the second protective layer 3 are made of metal, they can be made by casting, press molding, or the like. Next, the material for forming the radiation layer 4 is molded by tape molding, press molding, or the like and then fired to produce the radiation layer 4. Then, an adhesive layer having a low thermal resistance such as thermal grease is applied, the first protective layer 2 and the radiation layer 4 are pressure-bonded, and the second protective layer 3 is further provided as the thermal switch 1.

When the first protective layer 2 and the second protective layer 3 are made of ceramics, the protective layer can be produced by forming the material to be the protective layer by press molding, extrusion molding, or the like, followed by firing. Next, for example, a thick film is formed on the first protective layer 2 by coating, injection, or the like, and baked to produce the radiation layer 4. This is provided with a second protective layer 3 to form a thermal switch 1. In addition, the manufacturing method of the thermal switch 1 is not limited to these methods.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

(Example)
Perovskite-type manganese oxide (La _0.7 Sr _0.2 Ca _0.1 MnO ₃ ) was used as the radiation layer 4. The emissivity was 0.4 at 0 ° C. and 0.6 at 50 ° C. Using this perovskite type manganese oxide (La _0.7 Sr _0.2 Ca _0.1 MnO ₃ ) (radiation layer 4) powder, AD (aerosol deposition) using aluminum (first protective layer 2) as a substrate The radiation layer 4 having a thickness of 1 μm was formed by the method. A thermal switch 1 was prepared in which aluminum (second protective layer 3) was placed with a gap 5 of 100 μm so as to face the radiation layer 4. The way of heat transfer as a whole member (thermal switch 1) was evaluated using a heat flow meter. When one side of aluminum (first protective layer 2) is heated to 0 ° C and 50 ° C, the heat flow through the heat flow sensor attached to the other side aluminum (second protective layer 3) is measured. did.

When the heat flow rate in the state where the heat switch 1 is OFF, that is, 0 ° C. is 100, the heat flow rate in the state where the heat switch 1 is ON, ie, 50 ° C., is 125.

The thermal switch of the present invention can be used as a switch whose heat transferability varies depending on the temperature. For example, by providing a thermal switch in a battery pack or the like, the internal heat can be used effectively.

1: thermal switch, 2: first protective layer, 3: second protective layer, 4: radiation layer, 5: gap, 8: heat insulating material, 30: battery pack, 31: case.

Claims

A first protective layer that receives heat;
A radiation layer bonded onto the first protective layer and having an emissivity that changes as the temperature changes;
A second protective layer disposed opposite to the radiation layer and having a gap with the radiation layer, and receiving heat from the radiation layer;
With thermal switch.
The thermal switch according to claim 1, wherein the emissivity of the radiation layer changes by 0.2 or more when the temperature rises or falls.
The thermal switch according to claim 1 or 2, wherein the emissivity of the radiation layer changes stepwise.
The heat radiation according to any one of claims 1 to 3, wherein the radiation layer is formed of any one of a variable emissivity element, a Mott insulator, a metal-semiconductor phase transition material, and a metal-insulator phase transition material. switch.
The thermal switch according to claim 4, wherein the radiation layer is formed of a perovskite oxide.
The first protective layer or the second protective layer is formed of any one selected from the group consisting of an oxide, a nitride, a ceramic made of carbide, and a metal. The thermal switch described in.
The thermal switch according to any one of claims 1 to 6, wherein a gap between the radiation layer and the second protective layer is 1 nm or more and 1 mm or less.
The thermal switch according to any one of claims 1 to 7 is provided around a heat generation source for generating heat,
A temperature adjustment structure for adjusting a temperature due to the heat from the heat generation source by changing a heat dissipation state between a first temperature and a second temperature higher or lower than the first temperature.
A battery pack having the temperature adjustment structure according to claim 8.