Patent Publication Number: US-2020295419-A1

Title: Cooling member and power storage module

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority of Japanese patent application JP2016-052242 filed on Mar. 16, 2016, the entire contents of which are incorporated herein. 
     TECHNICAL FIELD 
     The technology described in this specification relates to a cooling member and a power storage module. 
     BACKGROUND ART 
     A cooling member including a sealed container and refrigerant enclosed therein has been known (refer Japanese Unexamined Patent Application Publication No. 2002-372388). The refrigerant absorbs heat from a heat source and is evaporated and turned into steam in the evaporation section of the sealed container. The steam moves within the sealed container to a condensation section and dissipates and is condensed into liquid. The liquid refrigerant moves within the enclosed container to the evaporation section. 
     Wicks are included within the sealed container to accelerate movement of the liquid refrigerant. The liquid refrigerant is moved to the evaporation section by capillary phenomenon caused by the wicks. 
     However, in the above configuration, if a sufficient amount of refrigerant is not moved to the evaporation section, the amount of liquid refrigerant may be insufficient in the evaporation section. Then, the heat from the heat source cannot be absorbed effectively and cooling properties of the cooling member may be lowered. 
     The present technology described in this specification has been completed in view of the circumstances described above. It is an object of the present technology to improve cooling properties of a cooling member. 
     SUMMARY 
     The technology described in this specification is a cooling member including an enclosing member including sheet members that are connected in a liquid tight manner, refrigerant enclosed in the enclosing member, and a medium arranged in the enclosing member and including a path through which the refrigerant moves, and the medium includes an evaporation section where the refrigerant is evaporated and turned into gas, the enclosing member includes a condensation section where the refrigerant that is in a gaseous state is condensed and turned into liquid, and the medium includes acceleration means that accelerates movement of the refrigerant that is in a liquid state to the evaporation section. 
     According to the above configuration, movement of the refrigerant, which is condensed and turned into liquid, from the condensation section to the evaporation section can be accelerated. Accordingly, the liquid state refrigerant is effectively supplied to the evaporation section and cooling efficiency of the cooling member can be improved. 
     According to the present technology described in this specification, cooling properties of a cooling member can be improved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view illustrating a power storage module according to a first embodiment. 
         FIG. 2  is an exploded perspective view illustrating the cooling member. 
         FIG. 3  is a cross-sectional view illustrating refrigerant. 
         FIG. 4  is a plan view illustrating refrigerant according to a second embodiment. 
         FIG. 5  is a plan view illustrating refrigerant according to a third embodiment. 
         FIG. 6  is a plan view illustrating refrigerant according to a fourth embodiment. 
     
    
    
     MODES FOR CARRYING OUT THE INVENTION 
     First Embodiment 
     A first embodiment according to a technology described in this specification will be described with reference to  FIGS. 1 to 3 . A power storage module  10  according to this embodiment includes a casing  11 , power storage elements  12  arranged in the casing  11 , and cooling members  13  that are arranged in the casing  11  and in contact with a part of an outer surface of each of the power storage elements  12 . In the following description, an X direction represents a right side, a Y direction represents a front side, and a Z direction represents an upper side. Symbols or numerals are put on one or some of the parts having the same shape and no symbols or numerals may be put on the rest of them. 
     The power storage module  10  is arranged such that a stacking direction in which the power storage elements  12  and the cooling members  13  are arranged faces an upper side. The upper side may be an upper side in a vertical direction or may be substantially a vertical upper side. 
     As illustrated in  FIG. 1 , the casing  11  is a substantially rectangular parallelepiped shape as a whole. The casing  11  includes a first case  14  and a second case  15 . The first case  14  is open toward a right side and has a substantially rectangular shape seen from the right side. The second case  15  is mounted on a right side with respect to the first case  14  and has a substantially rectangular cross-sectional shape and has a box shape opening toward a left side. A left side end of the second case  15  has a shape following that of a right side end of the first case  14 . 
     The first case  14  and the second case  15  may be made of any material such as synthetic resin or metal. The first case  14  and the second case  15  may be made of different materials or the same material. 
     The first case  14  and the second case  15  may be connected with a known method such as a locking structure including a locking member and an locked member, a screwing structure, and bonding with adhesive. The first case  14  and the second case  15  that are made of metal may be connected with a known method such as laser welding and brazing. In this embodiment, the first case  14  and the second case  15  are not connected in a liquid tight manner. However, the first case  14  and the second case  15  may be connected in a liquid tight manner. 
     A pair of power terminals  17  are mounted on a left end side section of the casing  11  and one of them projects upward and the other projects downward. The power terminals  17  are formed of a metal plate. 
     The power storage element  12  includes a pair of battery laminating sheets and a power storage component, which is not illustrated, between the laminating sheets, and edge sections of the battery laminating sheets are bonded in a liquid tight manner with a known method such as heat-welding. As illustrated in  FIG. 1 , a positive terminal  24  and a negative terminal  25  that are formed of a thin metal foil extend from an inside to an outside of the battery laminating sheets while being in contact with inner surfaces of the battery laminating sheets in a liquid tight manner. The positive terminals  24  and the negative terminals  25  project from left ends of the power storage elements  12  and are arranged in a front-rear direction at intervals. The positive terminals  24  and the negative terminals  25  are electrically connected to the power storage components, respectively. 
     As illustrated in  FIG. 1 , the power storage elements  12  (six in this embodiment) are arranged in an up-down direction. The power storage elements  12  arranged adjacent in the up-down direction include one positive terminal  24  next to another negative terminal  25  and one negative terminal  25  next to another positive terminal  24 . The positive terminal  24  and the negative terminal  25  that are next to each other are bent to be closer to each other and overlapped with each other and the positive terminal  24  and negative terminal  25  that are overlapped in a right-left direction are electrically connected to each other with a known method such as laser welding, ultrasonic welding, and brazing. Thus, the power storage elements  12  are connected in series. 
     In this embodiment, secondary batteries such as lithium ion secondary batteries and nickel hydride batteries or capacitors such as electric double layer capacitors and lithium ion capacitors may be used as the power storage elements  12 , and any power storage elements  12  can be used as appropriate. 
     The cooling member  13  includes refrigerant  27  and an enclosing member  26  that is formed in a liquid tight manner and the refrigerant  27  is enclosed inside the enclosing member  26 . An amount of the refrigerant  27  enclosed in the enclosing member  26  is determined as appropriate. In this embodiment, the refrigerant  27  is absorbed by a medium  37 A, which will be described later, and the symbol representing the refrigerant  27  illustrates the medium  37 A. One or some may be selected from a group of perfluorocarbon, hydrofluoroether, hydrofluoroketone, fluorine inert liquid, water, and alcohol such as methanol and ethanol and can be used as the refrigerant  27 . The refrigerant  27  may have an insulating property or may have conductivity. The cooling member  13  has a length dimension in the right-left direction that is greater than the length dimension of the power storage element  12 . 
     As illustrated in  FIG. 2 , the enclosing member  26  includes a first sheet member  28  and a second sheet member  29  having a substantially rectangular shape and the two sheet members are connected to each other in a liquid tight manner with a known method such as bonding, deposition, or welding. 
     Each of the first sheet member  28  and the second sheet member  29  includes a metal sheet and synthetic resin films on both surfaces of the metal sheet. Any metal such as aluminum, aluminum alloy, copper, or copper alloy may be selected as appropriate as the metal of the metal sheet. Any synthetic resin such as polyolefin such as polyethylene and polypropylene, polyester such as polybutylene terephthalate, and polyetylene terephthalate, and polyamide such as nylon  6  and nylon  6 ,  6  may be selected as appropriate as the synthetic resin of the synthetic resin film. 
     The enclosing member  26  of this embodiment is obtained by overlapping a surface of the first sheet member  28  having the synthetic resin film thereon and a surface of the second sheet member  29  having a synthetic resin film thereon and bonding the sheet members with heat-welding. 
     The enclosing member  26  has a contact section  30  on an outer surface thereof and the contact section  30  is in contact with the power storage element  12  to transfer heat therebetween. 
     The cooling member  13  includes a condensation section  40  at a projected section thereof projecting rightward from the power storage element  12 . The refrigerant  27  that is in a gaseous state is condensed and changed to liquid with phase transition in the condensation section  40 . In the condensation section  40 , the refrigerant  27  that is in a gaseous state and has relatively high temperature dissipates and is changed to liquid with phase transition within the enclosing member  26 . The released heat of condensation is transferred to the first sheet member  28  and the second sheet member  29  and the heat dissipates from the outer surfaces of the first sheet member  28  and the second sheet member  29  to the outside of the cooling member  13 . 
     The medium  37 A is included inside the enclosing member  26 . The medium  37 A is a substantially rectangular sheet. The medium  37 A includes minute spaces through which the refrigerant  27  that is in a liquid state and the refrigerant  27  that is in a gaseous state pass. 
     The medium  37 A is disposed in the enclosing member  26  over an area substantially equal to or larger than that of the contact section  30  of the enclosing member  26 . In this embodiment, the medium  37 A is disposed within the enclosing member  26  over an area larger than that of the contact section  30 . 
     The medium  37 A includes an evaporation section  41  that corresponds to the contact section  30  of the enclosing member  26 . The refrigerant  27  that is in a liquid state is evaporated by heat from the power storage element  12  and turns into gas in the evaporation section  41 . The refrigerant  27  that is evaporated absorbs heat of vaporization from the power storage element  12  and thus, the power storage element  12  is cooled down. 
       FIG. 3  illustrates a cross-sectional view of the medium  37 A. The medium  37 A includes a high affinity section  43 A having a high affinity for the refrigerant  27  that is in a liquid state and a low affinity section  44 A that is disposed on an upper surface of the high affinity section  43 A. In other words, the high affinity section  43 A and the low affinity section  44 A are stacked in a thickness direction of the medium  37 A (the up-down direction). In this embodiment, a configuration in which the high affinity section  43 A and the low affinity section  44 A are stacked is acceleration means  42  that accelerates movement of the refrigerant  27  that is in a liquid state to the evaporation section  41 . 
     The high affinity section  43 A and the low affinity section  44 A may be bonded with an adhesive layer or with heat fusing. The sections may be bonded with material through which the refrigerant  27  that is in a liquid state and the refrigerant  27  that is in a gaseous state can pass. The sections may be stacked with any other methods as necessary. 
     The low affinity section  44 A has a lower affinity for the refrigerant  27  that is in a liquid state than the high affinity section  43 A. In this embodiment, the low affinity section  44 A repels the refrigerant  27  that is in a liquid state. 
     The high affinity section  43 A is formed of material that can absorb the refrigerant  27 . The high affinity section  43 A may be formed of a cloth obtained by processing material that can absorb the refrigerant  27  into fibers or may be formed of a non-woven cloth. Examples of the non-woven cloth may include a fiber sheet, web (a thin film sheet made of only fibers), and batt (fibers of blanket). The material of the high affinity section  43 A may be natural fibers or synthetic fibers made of synthetic resin or may include both of the natural fibers and the synthetic fibers. In this embodiment, the high affinity section  43 A includes a resin cloth  45  made of synthetic fibers that can absorb the refrigerant  27 . 
     The low affinity section  44 A is formed of material that repels the refrigerant  27 . The low affinity section  44 A may be formed of a cloth obtained by processing material that repels the refrigerant  27  into fibers or formed of a non-woven cloth. Examples of the non-woven cloth may include a fiber sheet, web (a thin film sheet made of only fibers), and batt (fibers of blanket). The material of the low affinity section  44 A may be natural fibers or synthetic fibers made of synthetic resin or may include both of the natural fibers and the synthetic fibers. In this embodiment, the low affinity section  44 A includes a resin cloth  45  made of synthetic fibers that repels the refrigerant  27 . 
     In this embodiment, a thickness dimension of the high affinity section  43 A is same or substantially same as a thickness dimension of the low affinity section  44 A. The thickness dimension of the high affinity section  43 A may be greater than that of the low affinity section  44 A. The thickness dimension of the low affinity section  44 A may be greater than that of the high affinity section  43 A. 
     The high affinity section  43 A extends to the condensation section  40  of the enclosing member  26 . Therefore, the refrigerant  27  that is turned from gas into liquid with phase transition is absorbed by the high affinity section  43 A in the condensation section  40 . The refrigerant  27  absorbed by the high affinity section  43 A promptly moves within the high affinity section  43 A and reaches the evaporation section  41  of the medium  37 A. 
     The liquid state refrigerant  27  that reaches the evaporation section  41  receives heat from the power storage element  12  via the contact section  30 . Accordingly, the power storage element  12  is cooled down. 
     Furthermore, the refrigerant  27  absorbs heat of vaporization and turns into gas in the evaporation section  41 . Accordingly, the power storage element  12  is further cooled down. 
     The low affinity section  44 A repels the refrigerant  27  that is in a liquid state and therefore, the low affinity section  44 A is dry. The refrigerant  27  that is in a gaseous state promptly moves to the low affinity section  44 A. The low affinity section  44 A also extends to the condensation section  40  of the enclosing member  26 . Therefore, the refrigerant  27  that is in a gaseous state promptly moves within the low affinity section  44 A to the evaporation section  41 . 
     Operations and Effects of Embodiment 
     Next, operations and effects of this embodiment will be described. The cooling member  13  according to this embodiment includes the enclosing member  26  including the sheet members  28 ,  29  that are bonded in a liquid tight manner, the refrigerant  27  that is enclosed within the enclosing member  26 , and the medium  37 A that is disposed within the enclosing member and has paths through which the refrigerant  27  moves. The medium  37 A includes the evaporation section  41  where the refrigerant  27  is evaporated and turned into gas. The enclosing member  26  includes the condensation section  40  where the refrigerant  27  in a gaseous state is condensed and turned into liquid. The medium  37 A includes the acceleration means  42  that accelerates movement of the liquid state refrigerant  27  to the evaporation section  41 . 
     According to the above configuration, movement of the refrigerant  27 , which is condensed and turned into liquid, from the condensation section  40  to the evaporation section  41  can be accelerated. Accordingly, the liquid state refrigerant  27  is effectively supplied to the evaporation section  41  and cooling efficiency of the cooling member  13  can be improved. 
     According to this embodiment, the medium  37 A includes the high affinity section  43 A having an affinity for the liquid state refrigerant  27  and the low affinity section  44 A having an affinity for the liquid state refrigerant  27  lower than that of the high affinity section  43 A. 
     According to the above configuration, the refrigerant  27  that is in a liquid state is likely to be present in the high affinity section  43 A than the low affinity section  44 A. Therefore, the refrigerant  27  that is in a gaseous state is relatively likely to be present in the low affinity section  44 A and the refrigerant  27  that is in a liquid state is relatively likely to be present in the high affinity section  43 A. Accordingly, the refrigerant  27  that is in a gaseous state effectively moves within the low affinity section  44 A and the refrigerant  27  that is in a liquid state effectively moves within the high affinity section  43 A. As a result, the moment of the liquid state refrigerant  27  to the evaporation section  41  is accelerated and the cooling efficiency of the cooling member  13  can be improved. 
     According to this embodiment, the low affinity section  44 A has a property of repelling the liquid state refrigerant  27 . 
     According to the above configuration, the refrigerant  27  that is in a liquid state is repelled by the low affinity section  44 A and the refrigerant  27  that is in a gaseous state is likely to be present in the low affinity section  44 A. Accordingly, moving efficiency of the refrigerant  27  that is in a gaseous state within the low affinity section  44 A is improved. A greater amount of the refrigerant  27  that is in a liquid state is present within the high affinity section  43 A. As a result, a sufficient amount of the liquid state refrigerant  27  moves to the evaporation section  41  and the cooling efficiency of the cooling member  13  can be improved. 
     According to this embodiment, the medium  37 A is formed in a sheet and the high affinity section  43 A and the low affinity section  44 A are stacked in the thickness direction of the medium  37 A. 
     According to the above configuration, the liquid state refrigerant  27  receives heat from the heat source and is evaporated in the high affinity section  43 A. Then, the gaseous state refrigerant  27  promptly moves to the low affinity section  44 A that is disposed on the high affinity section  43 A. Accordingly, the movement of the liquid state refrigerant  27  is less likely to be blocked by the gaseous state refrigerant  27  in the high affinity section  43 A. As a result, the movement of the liquid state refrigerant  27  within the high affinity section  43 A is accelerated and the cooling efficiency of the cooling member  13  can be improved. 
     According to this embodiment, the medium  37 A includes the resin cloth  45  made of synthetic fibers. 
     According to the above configuration, the material of the synthetic fibers is properly selected to adjust the affinity for the liquid state refrigerant  27  easily. 
     The power storage module  10  of this embodiment includes the cooling member  13 , and the power storage element  12  including an outer surface at least a part of which is in contact with the cooling member  13 . 
     According to the above configuration, the power storage element  12  can be cooled down effectively by the cooling member  13 . 
     Second Embodiment 
     Next, the cooling member  13  of a second embodiment will be described with reference to  FIG. 4 . As illustrated in  FIG. 4 , a medium  37 B has a rectangular shape elongated in the right-left direction. The right end portion of the medium  37 B is arranged in the condensation section  40  of the enclosing member. Approximately four fifth of the medium  37 B in the left end portion is the evaporation section  41  that is disposed corresponding to the contact section  30 . 
     The medium  37 B includes multiple (three in this embodiment) high affinity sections  43 B and multiple (three in this embodiment) low affinity sections  44 B that are arranged alternately in the front-rear direction. Each of the high affinity sections  43 B and the low affinity sections  44 B has an elongated shape elongated in the right-left direction. The number of the high affinity sections  43 B may be same as or different from the number of the low affinity sections  44 B. In this embodiment, a configuration in which the high affinity sections  43 B and the low affinity sections  44 B are arranged in the front-rear direction is the acceleration means  42 . 
     In this embodiment, the front-rear direction length dimension of the high affinity section  43 B is same as or substantially same as that of the low affinity section  44 B. One of the front-rear direction length dimension of the high affinity section  43 B and that of the low affinity section  44 B may be greater than the other one. 
     In this embodiment, the right-left direction length dimension of the high affinity section  43 B is same as or substantially same as that of the low affinity section  44 B. One of the right-left direction length dimension of the high affinity section  43 B and that of the low affinity section  44 B may be greater than the other one. 
     In this embodiment, the low affinity section  44 B has a property of repelling the liquid state refrigerant  27 . 
     Configurations other than the above are substantially same as those of the first embodiment and the same symbols are put on the same parts and they will not be described. 
     In this embodiment, the medium  37 B is formed in a sheet and includes the high affinity sections  43  and the low affinity sections  44 B. The high affinity sections  43  extend from the evaporation section  41  of the medium  37 B toward the condensation section  40  of the enclosing member. The low affinity sections  44 B arranged adjacent to the high affinity sections  43 B and extend from the evaporation section  41  of the medium  37 B toward the condensation section  40  of the enclosing member. 
     According to the above configuration, the high affinity sections  43 B extend from the evaporation section  41  of the medium  37 B to the condensation section  40  of the enclosing member. Therefore, the refrigerant  27  that turns into liquid in the condensation section  40  effectively moves within the high affinity sections  43 B to the evaporation section  41 . 
     The refrigerant  27  that moves within the high affinity sections  43 B to the evaporation section  41  is changed from liquid into gas with phase transition in the evaporation section  41 . The refrigerant  27  that turns into gas can promptly move from the high affinity section  43 B to the low affinity section  44 B because the high affinity sections  43 B and the low affinity sections  44 B are arranged adjacent to each other. 
     The low affinity sections  44 B extend from the evaporation section  41  of the medium  37 B to the condensation section  40  of the enclosing member. Therefore, the refrigerant  27  that turns into gas effectively moves within the low affinity sections  44 B from the evaporation section  41  to the condensation section  40 . 
     According to the above configuration, a path for the gaseous state refrigerant  27  and a path for the liquid state refrigerant  27  are separately provided. Therefore, the moving efficiency of the gaseous state refrigerant  27  can be improved and the moving efficiency of the liquid state refrigerant  27  can be also improved. 
     According to this embodiment, the low affinity sections  44 B has a property of repelling the liquid state refrigerant  27 . 
     According to the above configuration, the refrigerant  27  that turns into liquid is repelled by the low affinity section  44 B and the gaseous state refrigerant  27  is likely to be present in the low affinity section  44 B. Accordingly, the moving efficiency of the gaseous state refrigerant  27  within the low affinity section  44 B is improved. A greater amount of the liquid state refrigerant  27  is likely to be present in the high affinity section  43 B. As a result, a sufficient amount of the liquid state refrigerant  27  can move to the evaporation section  41 , and the cooling efficiency of the cooling member  13  can be improved. 
     Third Embodiment 
     Next, the cooling member  13  according to a third embodiment will be described with reference to  FIG. 5 . The cooling member  13  according to the third embodiment includes a low affinity section  44 C and a high affinity section  43 C that are made of synthetic fibers having an affinity for the liquid state refrigerant  27 . The synthetic fibers of the high affinity section  43 C have a density greater than that of the synthetic fibers of the low affinity section  44 C. 
     The density of the synthetic fibers of the high affinity section  43 C may be set different from the density of the synthetic fibers of the low affinity section  44 C by changing the weight of the synthetic fibers per a unit area, that is, the mass of the sheet per a unit area. 
     In one medium  37 C, the high affinity section  43 C may be pressed with pressure greater than pressure with which the low affinity section  44 C is pressed such that the density of the synthetic fibers of the high affinity section  43 C may be increased than the density of the synthetic fibers of the low affinity section  44 C. 
     Configurations other than the above are substantially same as those of the second embodiment and the same symbols are put on the same parts and they will not be described. 
     The medium  37 C of this embodiment includes the high affinity section  43 C having an affinity for the liquid state refrigerant  27  and the low affinity section  44 C having a lower affinity for the liquid state refrigerant  27  compared to the high affinity section  43 C. The density of the synthetic fibers of the high affinity section  43 C differs from the density of the synthetic fibers of the low affinity section  44 C. 
     In a configuration including the medium  37 C formed of synthetic fibers having a relatively high affinity for the liquid state refrigerant  27 , the density of the synthetic fibers of the high affinity section  43 C is set high and the density of the synthetic fibers of the low affinity section  44 C is set low to form the high affinity section  43 C and the low affinity section  44 C in the medium  37 C. 
     In a configuration including the medium  37 C formed of synthetic fibers having a relatively low affinity for the liquid state refrigerant  27 , the density of the synthetic fibers of the high affinity section  43 C is set low and the density of the synthetic fibers of the low affinity section  44 C is set high to form the high affinity section  43 C and the low affinity section  44 C in the medium  37 C. 
     Thus, according to the above configuration, the high affinity section  43 C and the low affinity section  44 C can be formed in the medium  37 C with a simple method of providing the synthetic fibers with different densities. 
     Fourth Embodiment 
     Next, the cooling member  13  according to a fourth embodiment will be described with reference to  FIG. 6 . A medium  37 D according to this embodiment is formed in a rectangular shape elongated in the right-left direction. The right end section of the medium  37 D is arranged in the condensation section  40 . Approximately four fifth of the medium  37 D in the left end portion of the length dimension thereof with respect to the right-left direction is the evaporation section  41  that is disposed corresponding to the contact section  30 . 
     Approximately one fifth of the medium  37 D in the left end portion of the length dimension thereof with respect to the right-left direction is a high affinity section  43 D. 
     In this embodiment, a configuration including the high affinity section  43 D in the evaporation section  41  and a low affinity section  44 D on a condensation section  40  side is the acceleration means  42 . 
     The low affinity section  44 D and the high affinity section  43 D of the cooling member  13  are formed of the synthetic fibers having an affinity for the liquid state refrigerant  27  and the density of the synthetic fibers of the high affinity section  43 D is smaller than the density of the synthetic fibers of the low affinity section  44 D. 
     Configurations other than the above are substantially same as those of the first embodiment and the same symbols are put on the same parts and they will not be described. 
     In this embodiment, the medium  37 D includes a low affinity section  44 D near the condensation section  40  and a high affinity section  43 D that is a different section from the low affinity section  44 D and in the evaporation section  41 . 
     According to the above configuration, the refrigerant  27  that is in a liquid state can effectively move within the high affinity section  43 D to the evaporation section  41  since the high affinity section  43 D is included in the evaporation section  41 . An amount of the liquid state refrigerant  27  is relatively small in the section of the medium  37 D near the condensation section  40  because the low affinity section  44 D is included in the section near the condensation section  40 . Accordingly, the refrigerant  27  that is in a gaseous state can effectively move toward the condensation section  40 . As a result, the cooling efficiency of the cooling member  13  can be improved. 
     According to this embodiment, the density of synthetic fibers forming the high affinity section  43 D differs from the density of synthetic fibers forming the low affinity section  44 D. 
     In a configuration including the medium  37 D formed of synthetic fibers having a relatively high affinity for the liquid state refrigerant  27 , the density of synthetic fibers is set high in the high affinity section  43 D and the density of synthetic fibers is set low in the low affinity section  44 D such that the high affinity section  43 D and the low affinity section  44 D are formed in the medium  37 D. 
     In a configuration including the medium  37 D formed of synthetic fibers having a relatively low affinity for the liquid state refrigerant  27 , the density of synthetic fibers is set low in the high affinity section  43 D and the density of synthetic fibers is set high in the low affinity section  44 D such that the high affinity section  43 D and the low affinity section  44 D are formed in the medium  37 D. 
     Thus, according to the above configuration, the high affinity section  43 D and the low affinity section  44 D can be formed in the medium  37 D with a simple method of providing different densities with the synthetic fibers. 
     Other Embodiments 
     The present technology described in this specification is not limited to the embodiments, which have been described using the foregoing descriptions and the drawings. For example, embodiments described below are also included in the technical scope of the present technology described in this specification. 
     Following configurations may be preferable for embodiments of the technology described in this specification. 
     The medium may include a high affinity section having an affinity for the refrigerant that is in a liquid state and a low affinity section having a lower affinity for the refrigerant that is in a liquid state compared to the high affinity section. 
     According to the above configuration, the refrigerant that is in a liquid state is likely to be present in the high affinity section than the low affinity section. Therefore, the refrigerant that is in a gaseous state is relatively likely to be present in the low affinity section and the refrigerant that is in a liquid state is relatively likely to be present in the high affinity section. Accordingly, the refrigerant that is in a gaseous state effectively moves within the low affinity section and the refrigerant that is in a liquid state effectively moves within the high affinity section. As a result, the moment of the liquid state refrigerant to the evaporation section is accelerated and the cooling efficiency of the cooling member can be improved. 
     The low affinity section may have a property of repelling the refrigerant that is in a liquid state. 
     According to the above configuration, the refrigerant that is in a liquid state is repelled by the low affinity section and the refrigerant that is in a gaseous state is likely to be present in the low affinity section. Accordingly, moving efficiency of the refrigerant that is in a gaseous state within the low affinity section is improved. A greater amount of the refrigerant that is in a liquid state is present within the high affinity section. As a result, a sufficient amount of the liquid state refrigerant moves to the evaporation section and the cooling efficiency of the cooling member can be improved. 
     The medium may be formed in a sheet, and the high affinity section and the low affinity section may be stacked in a thickness direction of the medium. 
     According to the above configuration, the liquid state refrigerant receives heat from the heat source and is evaporated in the high affinity section. Then, the gaseous state refrigerant promptly moves to the low affinity section that is disposed on the high affinity section. Accordingly, the movement of the liquid state refrigerant is less likely to be blocked by the gaseous state refrigerant in the high affinity section. As a result, the movement of the liquid state refrigerant within the high affinity section is accelerated and the cooling efficiency of the cooling member can be improved. 
     The medium may be formed in a sheet, and the medium may include the high affinity section that extends from the evaporation section of the medium toward the condensation section of the enclosing member and the low affinity section that is adjacent to the high affinity section and extends from the evaporation section of the medium toward the condensation section of the enclosing member. 
     According to the above configuration, the high affinity sections extend from the evaporation section of the medium to the condensation section of the enclosing member. Therefore, the refrigerant that turns into liquid in the condensation section effectively moves within the high affinity sections to the evaporation section. 
     The refrigerant that moves within the high affinity sections to the evaporation section is changed from liquid into gas with phase transition in the evaporation section. The refrigerant that turns into gas can promptly move from the high affinity section to the low affinity section because the high affinity sections and the low affinity sections are arranged adjacent to each other. 
     The low affinity sections extend from the evaporation section of the medium to the condensation section of the enclosing member. Therefore, the refrigerant that turns into gas effectively moves within the low affinity sections from the evaporation section to the condensation section. 
     According to the above configuration, a path for the gaseous state refrigerant and a path for the liquid state refrigerant are separately provided. Therefore, the moving efficiency of the gaseous state refrigerant can be improved and the moving efficiency of the liquid state refrigerant can be also improved. 
     The medium may be formed in a sheet, and the medium may include the low affinity section in a section thereof near the condensation section and the high affinity section in a section that is different from the low affinity section and in the evaporation section. 
     According to the above configuration, the refrigerant that is in a liquid state can effectively move within the high affinity section to the evaporation section since the high affinity section is included in the evaporation section. An amount of the liquid state refrigerant is relatively small in the section of the medium near the condensation section because the low affinity section is included in the section near the condensation section. Accordingly, the refrigerant that is in a gaseous state can effectively move toward the condensation section. As a result, the cooling efficiency of the cooling member can be improved. 
     The medium may include a resin cloth made of synthetic fibers. 
     According to the above configuration, the material of the synthetic fibers is properly selected to adjust the affinity for the liquid state refrigerant easily. 
     The medium may include a high affinity section having an affinity for the refrigerant that is in a liquid state and a low affinity section having a low affinity for the refrigerant that is in a liquid state, and a density of the synthetic fibers included in the high affinity section may differ from a density of the synthetic fibers included in the low affinity section. 
     In a configuration including the medium formed of synthetic fibers having a relatively high affinity for the liquid state refrigerant, the density of the synthetic fibers of the high affinity section  4  is set high and the density of the synthetic fibers of the low affinity section is set low to form the high affinity section and the low affinity section in the medium. 
     In a configuration including the medium formed of synthetic fibers having a relatively low affinity for the liquid state refrigerant, the density of the synthetic fibers of the high affinity section is set low and the density of the synthetic fibers of the low affinity section is set high to form the high affinity section and the low affinity section in the medium. 
     Thus, according to the above configuration, the high affinity section and the low affinity section can be formed in the medium with a simple method of providing the synthetic fibers with different densities. 
     The technology described in this specification is a power storage module including the above cooling member, and a power storage element having an outer surface at least a part of which is in contact with the cooling member. 
     According to the above configuration, the power storage element can be cooled down by the cooling member effectively. 
     In the first embodiment, the first sheet member  28  and the second sheet member  29  of the cooling member  13  are laminating films each including a metal sheet and synthetic resin layered on both surfaces of the metal sheet. However, configurations of the first sheet member  28  and the second sheet member  29  may not be limited thereto. Each of the first sheet member and the second sheet member may be configured such that synthetic resin is layered on one surface of the metal sheet. Each of the first sheet member and the second sheet member may be formed of a metal sheet. The first sheet member and the second sheet member that are formed of metal sheets can be connected in a liquid tight manner with bonding, welding, and brazing. The first sheet member and the second sheet member may be formed of synthetic resin sheets. Any synthetic resin such as polyolefin such as polyethylene and polypropylene, polyester such as polybutylene terephthalate and polyethylene terephthalate, and polyamide such as nylon  6  and nylon  6 ,  6  may be selected as appropriate as the synthetic resin of the synthetic resin film. 
     In the above embodiments, one medium is arranged in the enclosing member  26 . However, it is not limited thereto and two or more media may be arranged in the enclosing member  26 . 
     In the above embodiments, the enclosing member  26  is formed by connecting the first sheet member  28  and the second sheet member  29 . However, it is not limited thereto and the enclosing member  26  may be formed from one sheet member. The sheet member may be folded and edges thereof may be connected in a liquid tight manner to form the enclosing member  26 . Three or more sheet members may be connected in a liquid tight manner to form the enclosing member  26 . 
     In the first embodiment, the medium  37 A is on an inner side of the condensation section  40  of the enclosing member  26 . However, it is not limited thereto and the medium  37 A may not be disposed on an inner side of the condensation section  40  but may be disposed only in a section corresponding to the contact section  30 . 
     It is to be understood that the foregoing is a description of one or more preferred exemplary embodiments of the invention. The invention is not limited to the particular embodiment(s) disclosed herein, but rather is defined solely by the claims below. Furthermore, the statements contained in the foregoing description relate to particular embodiments and are not to be construed as limitations on the scope of the invention or on the definition of terms used in the claims, except where a term or phrase is expressly defined above. Various other embodiments and various changes and modifications to the disclosed embodiment(s) will become apparent to those skilled in the art. All such other embodiments, changes, and modifications are intended to come within the scope of the appended claims. 
     As used in this specification and claims, the terms “for example,” “e.g.,” “for instance,” “such as,” and “like,” and the verbs “comprising,” “having,” “including,” and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation. 
     EXPLANATION OF SYMBOLS 
     
         
           10 : power storage module 
           12 : power storage element 
           13 : cooling member 
           26 : enclosing member 
           27 : refrigerant 
           28 : first sheet member 
           37 A,  37 B,  37 C,  37 D: medium 
           40 : condensation section 
           41 : evaporation section 
           42 : acceleration means 
           43 A,  43 B,  43 C,  43 D: high affinity section 
           44 A,  44 B,  44 C,  44 D: low affinity section 
           45 : resin cloth