Electricity storage unit

Abstract

The present disclosure relates to a power storage unit. An electricity storage cell is provided with an electrode body, a cell case that houses the electrode body, and a heat transfer film formed on the outer surface of the cell case. The outer surface includes a facing surface facing a cooler provided externally. The thermally conductive film is formed on the facing surface and has insulating properties and elasticity.

Description

Technical Field

[0001] This disclosure relates to energy storage units. Background Technology

[0002] For example, Japanese Patent Application Publication No. 2018-037343 discloses an energy storage device comprising an energy storage unit and a cooler. An insulating film is mounted on the surface of the energy storage unit. The energy storage unit is disposed on the cooler through the insulating film and a heat-conducting material. Summary of the Invention

[0003] The energy storage device disclosed in Japanese Patent Application Publication No. 2018-037343 has its energy storage unit disposed on a cooler with an insulating film and a heat-conducting material between it and the energy storage unit. When the energy storage unit expands and contracts, an air layer is created at the interface between the energy storage unit and the insulating film due to wrinkles and twists in the insulating film. As a result, heat transfer between the energy storage unit and the cooler is hindered.

[0004] This disclosure was made to solve the above-mentioned problems, and its purpose is to provide an energy storage device that can suppress heat transfer that hinders the energy storage unit and the cooler.

[0005] The first aspect of this disclosure provides an energy storage unit comprising an electrode body, a unit housing housing the electrode body, and a heat-conducting film formed on the outer surface of the unit housing. The outer surface includes a facing surface facing a cooler disposed externally. The heat-conducting film is formed on the facing surface and has insulation and elasticity.

[0006] The elasticity of the thermal conductive film of the energy storage unit of the first aspect of this disclosure is 5 points or more as indicated by a C-type hardness tester and 50 points or less as indicated by a A-type hardness tester, and the insulation breakdown voltage of the thermal conductive film is 5 kV / mm or more and 30 kV / mm or less.

[0007] The elasticity of the thermal conductive film of the energy storage unit of the first aspect of this disclosure contains insulating filler.

[0008] The first aspect of this disclosure includes an energy storage unit housed in an energy storage device, which has a housing and a cooler. The housing includes an upper cover and a lower housing. The lower housing has a base plate and a wall portion formed in a manner that rises from the base plate in a first direction. The base plate supports the energy storage unit in the first direction. The cooler is disposed on the base plate and is arranged in the first direction on the side opposite to the energy storage unit with respect to the base plate.

[0009] The energy storage unit of the first aspect of this disclosure further includes an exhaust valve and external terminals. The outer surface has: an end face, which is spaced apart from the opposing face in a first direction; and a peripheral surface, which connects the opposing face and the end face. The peripheral surface has a first side face and a second side face, which is spaced apart from the first side face in a second direction intersecting the first direction. The exhaust valve is formed on the outer surface, and the external terminals are formed on at least one of the first side face and the second side face. A heat-conducting film is formed away from the external terminals and the exhaust valve.

[0010] According to the energy storage unit disclosed herein, it is possible to suppress heat transfer obstacles between the energy storage unit and the cooler. Attached Figure Description

[0011] The features, advantages, and technical and industrial importance of exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, wherein like reference numerals denote like parts, and in the drawings:

[0012] Figure 1 This is a side view of a vehicle equipped with the energy storage device according to an embodiment of the present disclosure.

[0013] Figure 2 This is an exploded perspective view of the energy storage device in the embodiments of this disclosure.

[0014] Figure 3 This is a perspective view of the energy storage unit in an embodiment of this disclosure.

[0015] Figure 4 yes Figure 1 A sectional view of section IV-IV.

[0016] Figure 5 This is a perspective view showing a modified example of the energy storage unit in the embodiments of this disclosure. Detailed Implementation

[0017] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The same or equivalent parts will be labeled with the same reference numerals in the drawings, and their descriptions will not be repeated.

[0018] Figure 1 This is a schematic side view of a vehicle equipped with the energy storage device of this embodiment. Furthermore, Figure 1 The vertical direction H represents the vertical direction of vehicle 1. The width direction W represents the width direction of vehicle 1. The front-to-back direction D represents the front-to-back direction of vehicle 1. Furthermore, the vertical direction H and the width direction W are examples of the "first direction" and "second direction" of this disclosure, respectively.

[0019] Vehicle 1 includes a body 2 and an energy storage device 3. Vehicle 1 may include, for example, a PHEV (Plug-in Hybrid Electric Vehicle), a BEV (Battery Electric Vehicle), or an FCEV (Fuel Cell Electric Vehicle). The energy storage device 3 is mounted on the lower part of the body 2.

[0020] Figure 2 This is an exploded perspective view of the energy storage device according to an embodiment of the present disclosure. The energy storage device 3 includes a housing 10, a battery stack 50, and... Figure 4 Cooler 19 is shown.

[0021] The housing 10 includes an upper cover 11 and a lower cover 12. The housing 10 forms a housing space R defined by the upper cover 11 and the lower cover 12.

[0022] The upper cover 11 is formed to cover the lower shell 12, which is formed by opening upwards.

[0023] The lower housing 12 includes a base plate 13 and a wall 14. The base plate 13 supports the fuel cell stack 50 in the vertical direction H.

[0024] The wall portion 14 is formed to rise upward from the base plate 13 in the vertical direction H. The wall portion 14 has a peripheral wall 15 and a reinforcing portion 18. The peripheral wall 15 is formed to extend in a ring shape and extends upward from the outer periphery of the base plate 13 in the vertical direction H. The peripheral wall 15 has a first side wall 16 and a second side wall 17. The first side wall 16 and the second side wall 17 are formed to extend in the front-rear direction D and are arranged at intervals in the width direction W.

[0025] The reinforcing part 18 is formed to extend in the front-rear direction D. The reinforcing part 18 is configured to pass through the center of the first sidewall 16 and the second sidewall 17 in the width direction W.

[0026] The energy storage stack 50 is housed in the housing space R. The energy storage stack 50 is formed by a plurality of energy storage units 60. The plurality of energy storage units 60 are arranged in the front-to-back direction D. The energy storage units 60 are formed into a long rectangular parallelepiped shape in the width direction W.

[0027] Figure 3 This is a perspective view of the energy storage unit 60 according to an embodiment of the present disclosure. The energy storage unit 60 has a unit housing 70, external terminals 91, and an exhaust valve 92.

[0028] The unit housing 70 is formed as a cuboid. The unit housing 70 is made of a metal such as aluminum. The unit housing 70 has an outer surface 80. The outer surface 80 has a first end face 81, a second end face 82, and a peripheral surface 83. The first end face 81 and the second end face 82 are arranged at intervals in the vertical direction H. The second end face 82 is positioned near the base plate 13 compared to the first end face 81. The second end face 82 is the surface facing the base plate 13.

[0029] The peripheral surface 83 is formed to connect the first end face 81 and the second end face 82. The peripheral surface 83 has a first side face 83a, a second side face 83b, a first elongated surface 83c, and a second elongated surface 83d. The first side face 83a and the second side face 83b are arranged at intervals in the width direction W. The first elongated surface 83c and the second elongated surface 83d are arranged at intervals in the front-rear direction D. The first elongated surface 83c is formed to extend in the width direction W and is formed to connect one end of the first side face 83a to one end of the second side face 83b. The second elongated surface 83d is formed to extend in the width direction W and is formed to connect the other end of the first side face 83a to the other end of the second side face 83b. In the energy storage stack 50, at least one of the first elongated surface 83c and the second elongated surface 83d of the plurality of energy storage cells 60 faces the adjacent energy storage cell 60.

[0030] External terminal 91 and exhaust valve 92 are disposed on the first end face 81. Exhaust valve 92 opens when the gas pressure inside unit housing 70 reaches a certain level. That is, the first end face 81 where exhaust valve 92 is disposed constitutes the pressure relief surface of unit housing 70.

[0031] Figure 4 yes Figure 1 A cross-sectional view along section IV-IV. Cooler 19 is disposed on base plate 13 via heat transfer material 21. Cooler 19 is positioned on the side opposite to energy storage unit 60 in the vertical direction H, with base plate 13 as a reference. Cooler 19 faces second end face 82 across base plate 13. In this embodiment, cooler 19 cools energy storage unit 60 of energy storage stack 50. Cooling medium (oil, etc.) flows within cooler 19. Furthermore, the second end face 82 facing cooler 19 is an example of an "opposing surface" in this disclosure.

[0032] The housing 10 also has a common panel 20. The common panel 20 is located on the side opposite to the energy storage unit 60, with the base plate 13 as a reference in the vertical direction H. The common panel 20 is disposed on the base plate 13, separated by the cooler 19. The common panel 20 serves to protect the lower housing 12. The common panel 20 may also be formed as a flat plate.

[0033] The energy storage unit 60 also includes an electrode body 61 housed in the unit housing 70 and a heat-conducting film T formed on the outer surface 80 of the unit housing 70. Furthermore, the heat-conducting film T is formed on the outer surface 80, avoiding the external terminal 91 and the vent valve 92. More preferably, the heat-conducting film T is formed to avoid the external terminal 91 and the vent valve 92 and to cover the entire surface of the second end face 82 and the entire surface of the peripheral face 83 of the energy storage unit 60. This facilitates the dissipation of heat from inside the housing 10 to the outside.

[0034] The heat-conducting film T is elastic. The thickness of the heat-conducting film T formed on the outer surface 80 is 1 mm or more and 10 mm or less. By using such a heat-conducting film T, it is possible to suppress the formation of gaps between the energy storage unit 60 and the base plate 13. As a result, it is possible to suppress the obstruction of heat transfer between the energy storage unit 60 and the base plate 13 by gaps. In addition, the heat-conducting film T functions as an elastic body between adjacent energy storage units 60. Therefore, compared with the case where an elastic body is arranged between multiple energy storage units 60, the number of components in the energy storage device 3 can be reduced.

[0035] Here, the elasticity of the heat-conducting film T is defined as showing 5 or more points when measured using a C-type hardness tester based on JISK7312, and 50 or less points when measured using an A-type hardness tester based on JISK6253-3. Therefore, damage to the heat-conducting film T can be suppressed when assembling the energy storage unit 60 into the housing 10. Furthermore, the heat-conducting film T prevents obstruction of the close contact between the energy storage unit 60 and its adjacent components.

[0036] The thermal conductivity of the heat-conducting film T is 1.0 W / mK or higher and 30.0 W / mK or lower. By using such a heat-conducting film T, even without sandwiching a heat-transfer material between the energy storage unit 60 and the base plate 13, it is possible to suppress the obstruction of heat transfer between the energy storage unit 60 and the base plate 13. As a result, the number of components in the energy storage device 3 can be reduced. The heat-conducting film T may also contain insulating filler. The insulating filler is formed from materials such as inorganic compounds. More specifically, the insulating filler is formed from materials such as silicon compounds such as molten silica, metal oxides such as aluminum oxide and magnesium, or nitrogen compounds such as boron nitride and aluminum nitride. By including insulating filler in the heat-conducting film T, the thermal conductivity of the heat-conducting film T can be improved.

[0037] The thermally conductive film T possesses insulating properties. The insulation breakdown voltage of the thermally conductive film T is above 5 kV / mm and below 30 kV / mm. Furthermore, the inherent volume resistivity of the thermally conductive film T is 1.0 × 10⁻⁶. 10 Ω·cm or more and 1.0×10 17 Below Ω·cm. By using such a thermally conductive film T, it is possible to suppress the conduction between the energy storage unit 60 and adjacent energy storage units 60.

[0038] The heat-conducting film T covers the unit housing 70 after curing. For example, the heat-conducting film T is fixed to the unit housing 70 during the curing process. The heat-conducting film T is non-adhesive after curing. That is, the energy storage unit 60 housed in the housing space R is not bonded to the base plate 13. By using such a heat-conducting film T, the energy storage unit 60 can be easily detached from the energy storage device 3. Alternatively, the heat-conducting film T may not be fixed to the unit housing 70. Thus, the heat-conducting film T can be easily peeled off from the unit housing 70.

[0039] The material forming the thermally conductive film T is in a paste-like state when uncured. Preferably, the material forming the thermally conductive film T is thixotropic when uncured. The material forming the thermally conductive film T is a curable liquid material. The curable liquid material is, for example, a single-component or two-component potting material or interstitial filler. The material forming the thermally conductive film T is a material that is cured by any one of heating curing, room temperature curing, moisture curing, or ultraviolet curing. The material forming the thermally conductive film T is based on any one of silicone resin, epoxy resin, or polyurethane resin. By using such a material to form the thermally conductive film T, defects or damage to the thermally conductive film T can be repaired by touch-up. As a result, the increase in repair time can be suppressed compared to replacing the entire thermally conductive film T covering the energy storage unit 60. Here, the viscosity of the material forming the thermally conductive film T when uncured is 0.1 Pa·s or more and 500 Pa·s or less. Thus, the thermally conductive film T can be formed on the unit housing 70 by coating or impregnation. Furthermore, it can suppress the thinning of the film thickness due to dripping or other factors during the curing process of the heat-conducting film T.

[0040] In the above embodiments, an example is shown where the heat-conducting film T is formed on the entire surface of the outer surface 80, but this disclosure is not limited thereto. For example, the heat-conducting film T may not be formed on the first end face 81. Alternatively, the heat-conducting film T may be formed only on the surface of the outer surface 80 that is in contact with the adjacent energy storage unit 60 and the surface that is in contact with the base plate 13. More specifically, the heat-conducting film T may be formed only on at least one of the second end face 82, the first elongated surface 83c, and the second elongated surface 83d. Moreover, the heat-conducting film T may be formed only on a portion of the surface of the outer surface 80 facing the adjacent energy storage unit 60. By forming the heat-conducting film T on a portion, a gap is formed between the heat-conducting film T and the adjacent energy storage unit. This ensures spatial insulation and suppresses short circuits between adjacent energy storage units 60.

[0041] In the above embodiment, a heat-conducting film T is formed on the outer surface 80, avoiding the external terminal 91 and the exhaust valve 92. This prevents the functions of the external terminal 91 and the exhaust valve 92 from being impaired by the heat-conducting film T applied to the unit housing 70.

[0042] In the above embodiments, an example is shown where the exhaust valve 92 is disposed on the first end face 81, but this disclosure is not limited thereto. For example, as Figure 5 As shown, the exhaust valve 92 can also be located on the second end face 82.

[0043] In the above embodiments, an example is shown where the external terminal 91 is disposed on the first end face 81, but this disclosure is not limited thereto. For example, as Figure 5 As shown, the external terminal 91 can also be disposed on the first side 83a and the second side 83b. Alternatively, the external terminal 91 can be disposed on only one of the first side 83a and the second side 83b.

[0044] <Methods for forming thermally conductive film T>

[0045] Next, an example of a method for forming the heat-conducting film T of the energy storage unit 60 will be described. The method for forming the heat-conducting film T includes, in the following process sequence, a preparation process, a curing process, a coating process, and a drying process. The details of each process are described below.

[0046] In the preparation process, the energy storage unit 60 is prepared before the formation of the heat-conducting film T. In the curing process, the external terminals 91 and vent valve 92 of the energy storage unit 60 prepared in the preparation process are shielded. Additionally, in the preparation process, insulating filler is added to the uncured heat-conducting film T material and thoroughly mixed. In the coating process, the heat-conducting film T material is applied to the energy storage unit 60. Coating is performed by impregnation and coating. In the drying process, the applied heat-conducting film T material is dried, and the heat-conducting film T is cured. Through the above processes, the heat-conducting film T is formed on the outer surface 80 of the energy storage unit 60.

[0047] The embodiments disclosed herein should be considered illustrative in all respects and not restrictive. The scope of this disclosure is not shown by the description of the above embodiments, but by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

Claims

1. An energy storage unit, wherein, The energy storage unit includes an electrode body, a unit housing that houses the electrode body, and a heat-conducting film formed on the outer surface of the unit housing. The outer surface includes a facing surface that faces the externally disposed cooler. The heat-conducting film is formed on the opposing surfaces and has elasticity and insulation.

2. The energy storage unit according to claim 1, wherein, The elasticity of the heat-conducting membrane is above 5 points as indicated by a C-type hardness tester and below 50 points as indicated by a A-type hardness tester, and the insulation breakdown voltage of the heat-conducting membrane is above 5kV / mm and below 30kV / mm.

3. The energy storage unit according to claim 1, wherein, The heat-conducting membrane contains insulating filler.

4. The energy storage unit according to claim 1, wherein, The energy storage unit is housed in the energy storage device. The energy storage device includes a housing and the cooler. The housing includes an upper cover and a lower housing. The lower housing has a bottom plate and a wall portion formed so as to rise upright from the bottom plate in a first direction. The base plate supports the energy storage unit in the first direction. The cooler is disposed on the base plate and is positioned on the side opposite to the energy storage unit in the first direction with reference to the base plate.

5. The energy storage unit according to claim 1, wherein, The energy storage unit also includes an exhaust valve and external terminals. The outer surface has: end faces, which are spaced apart from the opposing surfaces in a first direction; and a peripheral surface, which connects the opposing surfaces to the end faces. The circumferential surface has a first side surface and second side surfaces arranged at intervals from the first side surface in a second direction intersecting the first direction. The exhaust valve is formed on the outer surface. The external terminal is formed on at least one of the first side and the second side. The heat-conducting membrane is formed to avoid the external terminals and the exhaust valve.

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