Electric vehicle storage battery heat retaining system

Abstract

To provide an electric vehicle storage battery heat retaining system capable of improving traveling performance of an electric vehicle by removing heat accumulation means in an environment in which heat retaining of a storage battery is not required.SOLUTION: An electric vehicle comprises: a storage battery B that supplies power to a motor and is chargeable; heat accumulation means 1 including a heat accumulation body H that is heated by actuation of a heater 2 and can accumulate heat using latent heat and sensible heat; first heat transfer means 3 and second heat transfer means 4 that transfer heat accumulated in the heat accumulation means 1 to the storage battery B; and control means 5 for controlling the actuation of the heater 2. Provided is an electric vehicle storage battery heat retaining system for heat retaining of the storage battery of the electric vehicle. The heat accumulation means 1 is made to be attachable to and detachable from the electric vehicle V.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a battery heat retention system for an electric vehicle, which is for keeping the battery of an electric vehicle equipped with a storage battery, a heat storage means, and the like warm. [Background technology]

[0002] Although electric vehicles equipped with storage batteries are considered to have a lower environmental impact than vehicles equipped with internal combustion engines such as internal combustion engines and have been gaining popularity in recent years, when used in cold regions or other places with low temperatures, the performance of the storage batteries deteriorates significantly, resulting in reduced driving distance and reduced output. To avoid such deterioration in the performance of the storage batteries, as disclosed in Patent Document 1, for example, a storage battery insulation system for electric vehicles has been proposed, which stores heat from an electric heater in a heat storage tank (heat storage means) and uses that heat to warm and maintain the temperature of the storage battery. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 5-124443 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned conventional technology, a relatively heavy heat storage means is installed in the electric vehicle even in environments where keeping the battery warm is not necessary (for example, summer), so there is a problem in that the unnecessary weight of the battery reduces the range of the electric vehicle and deteriorates its driving performance.

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide a battery insulation system for an electric vehicle that can remove the heat storage means in environments where keeping the battery warm is not necessary, thereby improving the driving performance of the electric vehicle. [Means for solving the problem]

[0006] The invention described in claim 1 is a battery insulation system for an electric vehicle for keeping the battery of an electric vehicle warm, comprising: a storage battery that supplies power to a motor and can be charged; heat storage means having a heat storage body that can be heated by operation of a heater and store heat as latent heat and sensible heat; heat transfer means that transfers the heat stored in the heat storage means to the storage battery; and control means that controls operation of the heater, wherein the heat storage means is detachable from the electric vehicle.

[0007] The invention described in claim 2 is characterized in that, in the battery insulation system for electric vehicles described in claim 1, the heat transfer means is made of copper or aluminum metal, or a heat pipe in which a liquid is vacuum-sealed inside the pipe.

[0008] The invention of claim 3 is characterized in that, in the battery insulation system for an electric vehicle of claim 1, the heat transfer means comprises a first heat transfer means that transfers heat from the heat storage means and a second heat transfer means that transfers the heat transferred by the first heat transfer means to the storage battery, and the first heat transfer means and the second heat transfer means are connected via a connector, thereby transferring the heat from the heat storage means to the storage battery.

[0009] The invention described in claim 4 is characterized in that, in the battery insulation system for an electric vehicle described in claim 1, the heater is operated while the heat storage means is removed from the electric vehicle, making it possible to store heat in the heat storage means.

[0010] The invention of claim 5 is characterized in that, in the battery insulation system for an electric vehicle of claim 1, the control means operates the heater to store heat in the heat storage means, and estimates the amount of heat stored in the heat storage means based on a resistance value when current is applied to the heater.

[0011] The invention of claim 6 is characterized in that, in the storage battery insulation system for an electric vehicle of claim 5, the control means stops power supply to the heater when the amount of heat stored in the heat storage means estimated based on the resistance value when power is supplied to the heater is equal to or greater than a predetermined value.

[0012] The invention described in claim 7 is characterized in that, in the battery insulation system for an electric vehicle described in claim 1, the control means operates the heater to store heat in the heat storage means, on the condition that the amount of electricity stored in the battery is equal to or greater than a predetermined value.

[0013] The invention of claim 8 is characterized in that in the storage battery insulation system for an electric vehicle of claim 1, the control means stops the supply of electricity to the heater when the outside air temperature is equal to or higher than a predetermined value.

[0014] The invention described in claim 9 is characterized in that, in the battery insulation system for electric vehicles described in claim 1, the heat storage body of the heat storage means has a core particle made of a latent heat storage material of Al or Al-Si alloy, and an oxide coating of the constituent elements of the core particle provided on the outer surface of the core particle.

[0015] The invention described in claim 10 is characterized in that, in the thermal insulation system for a storage battery for an electric vehicle described in claim 9, the oxide film has a dense first oxide film of the constituent elements of the core particle and a second oxide film of the constituent elements of the core particle formed on the outer surface of the first oxide film, and the first oxide film and the second oxide film are α-Al2O3. [Effects of the Invention]

[0016] According to the present invention, the heat storage means is detachable from the electric vehicle, and therefore the heat storage means can be removed in environments where keeping the storage battery warm is not required, thereby improving the driving performance of the electric vehicle. [Brief explanation of the drawings]

[0017] [Figure 1]1 is a schematic diagram showing an electric vehicle storage battery heat insulation system according to an embodiment of the present invention; [Figure 2] FIG. 10 is a schematic diagram showing a state in which the heat storage means in the electric vehicle storage battery insulation system is removed from the electric vehicle and is being heated. [Figure 3] Table showing the modes of the battery insulation system for electric vehicles [Figure 4] A time chart showing the control details of the battery heat retention system for electric vehicles. [Figure 5] A flowchart showing the control of the battery heat insulation system for an electric vehicle. [Figure 6] Schematic diagram showing the state of the charging mode in the electric vehicle storage battery insulation system [Figure 7] Schematic diagram showing the state of the heat storage mode in the electric vehicle storage battery insulation system. [Figure 8] FIG. 1 is a schematic diagram showing the off mode of the battery insulation system for an electric vehicle (when the heat storage means is removed from the electric vehicle). [Figure 9] Graph showing the relationship between the resistance value of the heater of the heat storage means and the heat storage capacity in the battery insulation system for electric vehicles. [Figure 10] Schematic diagram showing the heat storage body ((a) solid phase and (b) liquid phase) of the heat storage means in the electric vehicle battery insulation system. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The battery insulation system for an electric vehicle according to this embodiment is applied to an electric vehicle (BEV) equipped with a storage battery (battery) capable of supplying power to a drive motor, and as shown in FIG. 1, mainly comprises a storage battery B that supplies power to a motor M, a heat storage means 1 having a heat storage body H, a first heat transfer means 3 and a second heat transfer means 4, and a control means 5.

[0019] The electric vehicle V to which this invention is applied is capable of running using a motor M as a drive source, and does not have a drive source consisting of an internal combustion engine such as an internal combustion engine. The motor M is electrically connected to a storage battery B and is an electromagnetic motor that can obtain drive force from the electric power supplied from the storage battery B. The motor M according to this embodiment constitutes a main part of the vehicle's power unit, which includes an inverter, a power converter, etc.

[0020] The storage battery B is a secondary battery that supplies power to the motor M and can be repeatedly charged and discharged, and can be, for example, a lithium-ion battery, nickel-metal hydride battery, or lead-acid battery attached to the vehicle body. The storage battery B is electrically connected to an on-board charger 6, and can be charged by connecting the charging plug of a commercial power source D located in a parking space or the like to the on-board charger 6.

[0021] The heat storage means 1 has a heat storage body H that is heated by the operation of a heater 2 and can store heat using latent heat and sensible heat, and in this embodiment, as shown in Figures 6 to 8, is made up of a heat storage container 1a that houses the heat storage body H. The heat storage container 1a can be, for example, a vacuum insulated container, and is equipped with a heater 2 that generates heat when electricity is applied. The heater 2 is operated under the control of control means 5 and can heat and charge the heat storage body H when electricity is applied, and is made up of, for example, nichrome wire.

[0022] As shown in Figure 10, the heat storage body H has core particles Ha made of a latent heat storage material of Al or Al-Si alloy, and oxide films Hb of the constituent elements of the core particles Ha formed on the outer surfaces of the core particles Ha. In this embodiment, the oxide films Hb have a dense first oxide film of the constituent elements of the core particles Ha and a second oxide film of the constituent elements of the core particles Ha formed on the outer surface of the first oxide film, and the first oxide film and the second oxide film are α-Al2O3.

[0023] The Al-Si alloy constituting the core particles Ha of the heat storage material H can be controlled to have a low volumetric expansion coefficient during melting by adjusting the content ratio of Si, which has a negative volumetric expansion coefficient during melting. Furthermore, when heat is absorbed from the outside, the material undergoes a phase transformation from a solid phase (see FIG. 10(a)) to a liquid phase (see FIG. 10(b)), storing the absorbed heat as latent heat. Conversely, when the latent heat is released to the outside, the material undergoes a phase transformation from a liquid phase to a solid phase. This makes the heat storage material H stable during the heat storage cycle and usable even at relatively high temperatures, such as above 150°C, and allows the use of a heat storage material H with excellent heat storage energy density and thermal conductivity.

[0024] Furthermore, the core particles Ha of the heat storage body H according to this embodiment are configured to have a void N acting as a buffer between the core particles Ha and the oxide film Hb when the core particles Ha are in a solid phase (see FIG. 1(a)). As a result, the volume expansion of the core particles Ha when they are transformed from a solid phase to a liquid phase fills the void N (space buffer) that existed in the solid phase, and the components of the dissolved latent heat storage material (Al or Al-Si alloy) remain inside the space covered by the oxide film Hb.

[0025] The oxide coating Hb can be an oxide of a metal that is a component of the latent heat storage material of the core particles Ha, or an oxide containing a component of a chemical solution used in the chemical coating treatment described below. For example, if the latent heat storage material that becomes the core particles Ha is an Al-Si alloy, the oxide coating Hb can be an oxide of Al, which is a component of the alloy. In this case, α-Al2O3 is chemically stable and is suitable for the oxide coating Hb.

[0026] The heat transfer means has a first heat transfer means 3 and a second heat transfer means 4, and transfers the heat stored in the heat storage means 1 to the storage battery B. It is made of copper or aluminum metal, or a heat pipe with a small amount of liquid (working fluid) vacuum-sealed inside the pipe. A heat pipe is a hollow pipe with a porous material attached to its inner surface that contains a liquid that can transfer heat using latent heat, and is capable of effective heat transfer by causing heat transfer due to the latent heat of evaporation and condensation in addition to temperature changes in the liquid.

[0027] 1 , the first heat transfer means 3 is inserted into the heat storage container 1a of the heat storage means 1 and transfers heat from the heat storage means 1 to the outside, and is attached to a connector C1. In addition to the first heat transfer means 3, a heater 2 is also attached to the connector C1. The second heat transfer means 4 is inserted into the container Y that accommodates the storage battery B and transfers the heat transferred by the first heat transfer means 3 to the storage battery B, and is attached to a connector C2. The connector C2 is electrically connected to the control means 5.

[0028] However, by connecting the connector C1 on which the heater 2 and the first heat transfer means 3 are formed and the connector C1 on which the second heat transfer means 4 is formed, the first heat transfer means 3 and the second heat transfer means 4 are linked via these connectors C1 and C2, and heat from the heat storage means 1 can be transferred to the storage battery B. In addition, in this embodiment, by connecting the connector C1 and the connector C2, power supplied from the control means 5 is supplied to the heater 2 via the connectors C1 and C2.

[0029] The control means 5 is made up of a microcomputer or the like arranged in the electric vehicle V, and is capable of controlling the operation of, for example, the heater 2. Furthermore, the control means 5 is operated by power supplied from the storage battery B and the on-board charger 6, and is electrically connected to an outside air temperature sensor 9, so that a value detected by the outside air temperature sensor 9 can be input thereto.

[0030] Here, the heat storage means 1 in the electric vehicle storage battery insulation system according to this embodiment is detachable from the electric vehicle V. Specifically, the heat storage container 1a of the heat storage means 1 is fixed to an arbitrary position on the electric vehicle V by fastening means or the like, and can be removed from the electric vehicle V by releasing the fastening by the fastening means and disconnecting the connector C1 from the connector C2 as shown in Fig. 8 .

[0031] Furthermore, the heat storage means 1 is capable of storing heat by operating the heater 2 while being removed from the electric vehicle V. That is, as shown in Fig. 2, the heat storage means 1 according to this embodiment can be removed integrally with the connector C1 on which the heater 2 and the first heat transfer means 3 are formed, and the connector C1 can be connected to a separate connector C3.

[0032] The connector C3 is electrically connected to a control means 7 (consisting of a microcomputer similar to the control means 5) that controls the operation of the heater 2. The control means 7 is electrically connected to a charger 8 (a charger separate from the on-board charger 6), and by connecting the charging plug of the commercial power source D to the charger 8, power can be supplied to the heater 2.

[0033] On the other hand, if it is necessary to keep the storage battery B warm after removing the heat storage means 1 from the electric vehicle V, the heat storage container 1a of the heat storage means 1 can be placed in an arbitrary position, and after connecting the connector C1 and the connector C2 as shown in Fig. 1, the heat storage means 1 can be fixed with a fastening means or the like, thereby attaching the heat storage means 1 to the electric vehicle V. In this way, the heat storage means 1 according to this embodiment can be attached and detached to and from the electric vehicle V at will, depending on the need to keep the storage battery B warm.

[0034] Furthermore, the control means 5 according to this embodiment is configured to energize the heater 2 to heat the heat storage body H, and to estimate the amount of heat stored in the heat storage means 1 based on the resistance value when the heater 2 is energized. That is, when the heater 2 is operated to store heat in the heat storage means 1, it is known that the relationship shown in Fig. 9 holds between the resistance value (Ω) of the heater 2 and the amount of heat stored in the heat storage means 1 (SOCH (%)). Therefore, if the resistance value when the heater 2 is energized is detected, the amount of heat stored in the heat storage means 1 can be estimated based on the detected resistance value. Note that α in the graph of Fig. 9 indicates the change in resistance value during the process of phase transformation of the core particles Ha in the heat storage body H.

[0035] The control means 5 according to this embodiment is configured to stop the supply of electricity to the heater 2 when the amount of heat stored in the heat storage means 1 estimated based on the resistance value when the heater 2 is energized is equal to or greater than a first predetermined value (predetermined value 1 near the upper limit in the graph of FIG. 9). In addition, the control means 5 according to this embodiment is configured to operate the heater 2 to store heat in the heat storage means 1, on the condition that the amount of stored electricity in the storage battery B (SOCB) is equal to or greater than a predetermined value. Furthermore, the control means 5 according to this embodiment is configured to stop the supply of electricity to the heater 2 when the outside air temperature detected by the outside air temperature sensor 9 is equal to or greater than a predetermined value.

[0036] 4 shows a time chart illustrating the parameters of the vehicle speed, the amount of stored electricity, the amount of stored heat, and the interior temperature of the vehicle V according to the above embodiment, as well as the operating state of the heater 2. Note that "FCCNO" (function circuit control number) in the table in the figure corresponds to "FCCNO" in the tables showing the control modes in FIGS. 3 and 5.

[0037] Next, the control of the control means 5 according to this embodiment will be described with reference to the flowchart of FIG. After obtaining the amount of stored electricity (SOCB) of storage battery B in S1, it is determined in S2 whether or not the heat storage container 1a is attached to the electric vehicle V (the connection between coupler C1 and coupler C2 is determined using the electric circuit of heater 2), and if it is determined that the heat storage container 1a is attached to the electric vehicle V, the amount of stored heat (SOCH) is obtained in S3, and if it is determined that the heat storage container 1a is not attached to the electric vehicle V, the process proceeds to S10 and FCCNO=3 is set.

[0038] On the other hand, if the amount of stored heat (SOCH) is acquired in S3, a determination is made in S4 as to whether the outside air temperature is lower than a predetermined value, and if it is determined that the outside air temperature is lower than the predetermined value, a determination is made in S5 as to whether the charging plug of the commercial power source D is attached to the on-board charger 6 of the electric vehicle V. If it is determined in S5 that the charging plug of the commercial power source D is attached to the on-board charger 6 of the electric vehicle V, a determination is made in S6 as to whether the amount of stored power (SOCB) of the storage battery B is greater than a predetermined value, and if it is determined that the amount of stored power (SOCB) of the storage battery B is greater than the predetermined value, a determination is made in S7 as to whether the amount of stored heat (SOCH) is smaller than a predetermined value 1.

[0039] If it is determined in S7 that the amount of stored heat (SOCH) is smaller than the predetermined value 1, the process proceeds to S8, where FCCNO is set to 1. If it is determined in S4 that the outside air temperature is not lower than the predetermined value, if it is determined in S5 that the charging plug of the commercial power source D is not attached to the on-board charger 6 of the electric vehicle V, if it is determined in S6 that the amount of stored power (SOCB) of the storage battery B is not larger than the predetermined value, or if it is determined in S7 that the amount of stored heat (SOCH) is not smaller than the predetermined value 1, the process proceeds to S9, where FCCNO is set to 2.

[0040] Once the FCCNO is set through the above steps, heater control of the heater 2 is performed based on the FCCNO in S11, and the series of controls is completed.

[0041] Next, the control based on the set FCCNO will be specifically described with reference to the control table of FIG. When FCCNO=1, the charging mode (see FIG. 6) is set and the heater 2 is activated (ON). When FCCNO=2, the battery warming mode (see FIG. 7) is set and the heater 2 is stopped (OFF). When FCCNO=3, the off mode (see FIG. 8) is set and the heater 2 is stopped (OFF). In the off mode, the heat storage means 1 is removed from the electric vehicle V.

[0042] According to the storage battery insulation system for an electric vehicle according to the above embodiment, the heat storage means 1 is detachable from the electric vehicle V. Therefore, in an environment where it is not necessary to keep the storage battery B warm, the heat storage means 1 can be removed to improve the running performance of the electric vehicle V. For example, in winter when it is necessary to keep the storage battery B warm, the heat storage means 1 can be attached to the electric vehicle V, and in summer when it is not necessary to keep the storage battery B warm, the heat storage means 1 can be removed from the electric vehicle V.

[0043] In addition, the heat transfer means (first heat transfer means 3 and second heat transfer means 4) in this embodiment are made of copper or aluminum metal, or a heat pipe with a small amount of liquid vacuum-sealed inside the pipe, so that the heat of the heat storage means 1 can be efficiently transferred to the storage battery B and the battery can be reliably kept warm.

[0044] Furthermore, the heat transfer means according to this embodiment comprises a first heat transfer means 3 that transfers the heat of the heat storage means 1, and a second heat transfer means 4 that transfers the heat transferred by the first heat transfer means 3 to the storage battery B. The first heat transfer means 3 and the second heat transfer means 4 are connected via connectors C1 and C2, thereby transferring the heat of the heat storage means 1 to the storage battery B. Therefore, the heat storage means 1 can be easily attached to or detached from the electric vehicle V by connecting or disconnecting the connectors C1 and C2.

[0045] Furthermore, since the heater 2 can be operated to store heat in the heat storage means 1 in this embodiment while the heat storage means 1 is removed from the electric vehicle V, heat can be stored in the heat storage means 1 while the heat storage means 1 is maintained in a state where it is removed from the electric vehicle V.

[0046] In addition, the control means 5 operates the heater 2 to store heat in the heat storage means 1, and estimates the amount of heat stored in the heat storage means 1 based on the resistance value when current is applied to the heater 2, so that it is possible to easily grasp the amount of heat stored in the heat storage means 1 without requiring a separate sensor or the like for detecting the amount of heat stored in the heat storage means 1. Furthermore, the control means 5 according to this embodiment stops the supply of current to the heater 2 when the amount of heat stored in the heat storage means 1 estimated based on the resistance value when current is applied to the heater 2 is equal to or greater than a predetermined value, so that it is possible to prevent the heat storage means 1 from overheating.

[0047] Furthermore, the control means 5 according to this embodiment operates the heater 2 to store heat in the heat storage means 1 on the condition that the amount of electricity stored in the storage battery B is equal to or greater than a predetermined value, and therefore can prioritize charging of the storage battery B over heat storage by the heat storage means 1, depending on the state of electricity stored in the storage battery B. Furthermore, the control means 5 according to this embodiment stops power supply to the heater 2 when the outside air temperature is equal to or greater than a predetermined value, and therefore can prevent unnecessary heat charging in an environment where keeping the storage battery B warm is not required.

[0048] Furthermore, the heat storage body H of the heat storage means 1 according to this embodiment has core particles Ha made of a latent heat storage material of Al or an Al-Si alloy, and an oxide coating Hb of the constituent elements of the core particles Ha formed on the outer surface of the core particles Ha, so that heat can be efficiently stored by utilizing the latent heat and sensible heat of the core particles Ha.

[0049] Furthermore, the oxide film Hb has a dense first oxide film of the constituent elements of the core particle Ha and a second oxide film of the constituent elements of the core particle Ha formed on the outer surface of the first oxide film, and since the first oxide film and the second oxide film are α-Al2O3, a chemically stable oxide film Hb can be utilized.

[0050] Although the present embodiment has been described above, the present invention is not limited to this, and for example, the electric vehicle V may be applied to industrial vehicles such as motorcycles, buggies, automobiles, trucks, trailers, campers, forklifts, or tractors, or may be an electric vehicle equipped with other types of storage batteries such as fuel cells. Furthermore, the heat storage body of the heat storage means is not limited to that of the present embodiment, and other types of heat storage bodies that utilize latent heat and sensible heat may be used. [Industrial Applicability]

[0051] The present invention can be applied to heating systems for electric vehicles having the same purpose as the present invention, such as systems with different external shapes or systems with additional functions. [Explanation of symbols]

[0052] 1 Heat storage means 1a Heat storage container 2 heaters 3. First heat transfer means 4 Second heat transfer means 5. Control measures 6 On-board charger 7 Control Measures 8 charger 9. Outside air temperature sensor V Electric Vehicle B. Storage battery C1 First connector C2 Second Connector D Commercial power H Heat storage body Ha core particle Hb oxide film N void

Claims

1. a rechargeable battery that supplies power to the motor; a heat storage means having a heat storage body that is heated by the operation of a heater and can store latent heat and sensible heat; a heat transfer means for transferring the heat stored in the heat storage means to the storage battery; a control means for controlling the operation of the heater; A battery insulation system for an electric vehicle for keeping the battery of the electric vehicle warm, comprising: The heat storage device is detachable from the electric vehicle.

2. 2. The battery heat insulation system for an electric vehicle according to claim 1, wherein the heat transfer means comprises a heat pipe made of metal such as copper or aluminum, or a pipe in which a liquid is vacuum-sealed.

3. 2. The battery insulation system for an electric vehicle according to claim 1, wherein the heat transfer means comprises first heat transfer means that transfers heat from the heat storage means and second heat transfer means that transfers the heat transferred by the first heat transfer means to the storage battery, and the first heat transfer means and the second heat transfer means are connected via a connector to transfer the heat from the heat storage means to the storage battery.

4. 2. The battery heat insulation system for an electric vehicle according to claim 1, wherein the heater is operated in a state where the heat storage means is removed from the electric vehicle, thereby enabling heat storage in the heat storage means.

5. 2. The battery insulation system for an electric vehicle according to claim 1, wherein the control means operates the heater to store heat in the heat storage means, and estimates the amount of heat stored in the heat storage means based on a resistance value when current is applied to the heater.

6. 6. The battery insulation system for an electric vehicle according to claim 5, wherein the control means stops power supply to the heater when the amount of heat stored in the heat storage means estimated based on a resistance value when power is supplied to the heater is equal to or greater than a predetermined value.

7. 2. The battery insulation system for an electric vehicle according to claim 1, wherein the control means operates the heater to store heat in the heat storage means on the condition that the amount of electricity stored in the battery is equal to or greater than a predetermined value.

8. 2. The battery heat insulation system for an electric vehicle according to claim 1, wherein the control means stops power supply to the heater when the outside air temperature is equal to or higher than a predetermined value.

9. The heat storage body of the heat storage means has a core particle made of a latent heat storage material of Al or an Al-Si alloy, and an oxide coating of the constituent elements of the core particle provided on the outer surface of the core particle. The battery insulation system for an electric vehicle according to claim 1.

10. The oxide film has a dense first oxide film of the constituent elements of the core particle and a second oxide film of the constituent elements of the core particle provided on the outer surface of the first oxide film, and the first oxide film and the second oxide film are made of α-Al ２ O ３ 10. The battery heat insulation system for an electric vehicle according to claim 9, wherein:

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