Patent Publication Number: US-2023140244-A1

Title: Power supply device and vehicle and power storage device having same

Description:
TECHNICAL FIELD 
     The present disclosure relates to a power supply device, and vehicle and a power storage device each equipped with the power supply device. 
     BACKGROUND ART 
     A power supply device is used as a power supply device for driving an electric vehicle, a power supply device for power storage, or the like. In such a power supply device, a plurality of chargeable and dischargeable battery cells are stacked, the plurality of battery cells are connected in series or in parallel, and electric power is extracted from a total output terminal. 
     Since the power supply device is used in various environments, water may enter the power supply device. Even when an outer covering case having high sealability is used, dew condensation water may be generated in the outer covering case due to a temperature difference. When water accumulates inside the power supply device, there is a possibility that a short circuit occurs between the battery cells having a potential difference via water. 
     In such a power supply device, it is necessary to prevent unintended conduction due to dew condensation, water entered from the outside, or the like. In particular, in a power supply device constituting a battery stack in which a large number of battery cells are stacked, a structure for avoiding a liquid junction is required to enhance safety. 
     CITATION LIST 
     Patent Literature 
     
         
         PTL 1: WO 2013/179796 A 
       
    
     SUMMARY OF THE INVENTION 
     Technical Problem 
     An object of one aspect of the present invention is to provide a power supply device in which unintended conduction hardly occurs even when dew condensation occurs, a vehicle and a power storage device including the power supply device. 
     Solution to Problem 
     A power supply device according to an aspect of the present invention is a power supply device including: a battery stack body in which a plurality of battery cells are stacked, each of the battery cells including an electrode terminal formed on a top surface of the battery cell; a pair of end plates that respectively cover respective end surfaces in a stacking direction of the battery stack; a fastening member that fastens the pair of end plates to each other; and an insulating member interposed between a side surface of the battery stack and the fastening member, wherein the insulating member includes a groove extending in the stacking direction of the battery stack on a surface facing the battery stack. 
     Advantageous Effect of Invention 
     According to a power supply device according to an aspect of the present invention, even when dew condensation water is generated, drainage can be urged by a groove provided in an insulating member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view illustrating a power supply device according to a first exemplary embodiment of the present invention. 
         FIG.  2    is an exploded perspective view of the power supply device illustrated in  FIG.  1   . 
         FIG.  3    is an enlarged schematic cross-sectional view illustrating an interface between a battery stack and an insulating member of the power supply device according to the first exemplary embodiment. 
         FIG.  4    is an enlarged schematic cross-sectional view illustrating an interface between a battery stack and an insulating member of a power supply device according to a second exemplary embodiment. 
         FIG.  5    is an enlarged schematic cross-sectional perspective view illustrating a groove shape formed in an insulating member of a power supply device according to a third exemplary embodiment. 
         FIG.  6    is an enlarged schematic cross-sectional view illustrating an interface between a battery stack and an insulating member of a power supply device according to a fourth exemplary embodiment. 
         FIG.  7    is an enlarged schematic cross-sectional view illustrating a groove shape formed in an insulating member of a power supply device according to a fifth exemplary embodiment. 
         FIG.  8    is an enlarged schematic cross-sectional view illustrating a groove shape formed in an insulating member of a power supply device according to a sixth exemplary embodiment. 
         FIG.  9    is a block diagram illustrating an example in which a power supply device is mounted on a hybrid automobile that travels by an engine and a motor. 
         FIG.  10    is a block diagram illustrating an example in which a power supply device is mounted on an electric automobile that travels only by a motor. 
         FIG.  11    is a block diagram illustrating an example of application to a power supply device for power storage. 
     
    
    
     DESCRIPTION OF EMBODIMENT 
     Exemplary embodiments of the present invention may be specified by the following configurations. 
     In a power supply device according to an exemplary embodiment of the present invention, in addition to the above configuration, the groove is a groove including a width in which dew condensation water is sucked due to a capillary phenomenon. With the above configuration, when dew condensation water is generated, the dew condensation water is guided to the groove by the capillary phenomenon, and drainage of the dew condensation water can be promoted. 
     In the power supply device according to another exemplary embodiment of the present invention, in addition to any of the above configurations, the groove is a groove including a width of 0.01 mm to 1.0 mm. 
     In the power supply device according to another exemplary embodiment of the present invention, in addition to any of the configurations described above, the insulating member includes a water-repellent coating film on a part or an entire surface of the insulating member. 
     In the power supply device according to another exemplary embodiment of the present invention, in addition to any of the configurations described above, the groove includes a step formed toward an opening surface of the groove shape in a cross-sectional view orthogonal to an extending direction of the groove shape. 
     In the power supply device according to another exemplary embodiment of the present invention, in addition to any of the configurations described above, the groove includes both ends, at least one of both the ends including a shape that expands toward a discharge direction. 
     In the power supply device according to another exemplary embodiment of the present invention, in addition to any of the configurations described above, the insulating member includes a flat plate covering a side surface of the battery stack and a covering part covering a bottom surface of the battery stack, and the flat plate and the covering part extend in the stacking direction of the battery stack, and the groove is provided on a surface of the covering part facing the battery stack. 
     In the power supply device according to another exemplary embodiment of the present invention, in addition to any of the configurations described above, the insulating member includes a flat plate covering a side surface of the battery stack and a covering part covering a bottom surface of the battery stack, and the flat plate and the covering part extend in the stacking direction of the battery stack, and the groove is provided on a surface of the flat plate facing the battery stack. 
     In the power supply device according to another exemplary embodiment of the present invention, in addition to any of the above configurations, the groove is formed in a linear shape inclined with respect to an extending direction of the flat plate. 
     A vehicle according to still another exemplary embodiment of the present invention is a vehicle including any of the above power supply devices, the power supply device, a motor for traveling that is supplied with electric power from the power supply device, a vehicle body on which the power supply device and the motor are mounted, and wheels that are driven by the motor to cause the vehicle body to travel. 
     A power storage device according to still another exemplary embodiment of the present invention is a power storage device including any of the above power supply devices, the power supply device, and a power supply controller that controls charging and discharging of the power supply device, wherein the power supply controller enables charging of each of the battery cells with electric power from an outside and controls charging to the battery cell. 
     Exemplary embodiments of the present invention will be hereinafter described with reference to the drawings. However, the exemplary embodiments described below are examples for embodying the technical idea of the present invention, and the present invention is not limited to the exemplary embodiments described below. Further, in the present specification, members indicated in the claims are not limited to the members of the exemplary embodiments. In particular, the dimensions, materials, shapes, and the relative arrangement of the constituent members described in the exemplary embodiments are not intended to limit the scope of the present invention only thereto unless otherwise specified and are merely illustrative examples. Note that the sizes and positional relationships of the members illustrated in the drawings may be exaggerated for clarity of description. Further, in the following description, the same names and marks indicate the same or similar members, and detailed description will be appropriately omitted. Furthermore, the elements constituting the present invention may be configured such that a plurality of elements are constituted of the same member to form one member that functions as the plurality of elements, or conversely, a function of one member can be shared and achieved by a plurality of members. In addition, the description in some examples or exemplary embodiments may be applied to other examples, exemplary embodiments, and the like. 
     The power supply device according to the exemplary embodiments is used in various applications including a power source to be equipped on a hybrid automobile, an electric automobile, or other electric vehicles to supply electric power to a drive motor, a power source that stores power generated by natural energy such as solar power generation and wind power generation, and a power source for storing midnight electric power, and in particular, used as a power source suitable for large-power, large-current applications. In the following example, the exemplary embodiments applied to a power supply device for driving an electric vehicle will be described. 
     Exemplary embodiments of the present invention will be hereinafter described with reference to the drawings. However, the exemplary embodiments described below are examples for embodying the technical idea of the present invention, and the present invention is not limited to the exemplary embodiments described below. Further, in the present specification, members indicated in the claims are not limited to the members of the exemplary embodiments. In particular, the dimensions, materials, shapes, and the relative arrangement of the constituent members described in the exemplary embodiments are not intended to limit the scope of the present invention only thereto unless otherwise specified and are merely illustrative examples. Note that the sizes and positional relationships of the members illustrated in the drawings may be exaggerated for clarity of description. Further, in the following description, the same names and marks indicate the same or similar members, and detailed description will be appropriately omitted. Furthermore, the elements constituting the present invention may be configured such that a plurality of elements are constituted of the same member to form one member that functions as the plurality of elements, or conversely, a function of one member can be shared and achieved by a plurality of members. In addition, the description in some examples or exemplary embodiments may be applied to other examples, exemplary embodiments, and the like. 
     The power supply device according to the exemplary embodiments is used in various applications including a power source to be equipped on a hybrid automobile, an electric automobile, or other electric vehicles to supply electric power to a drive motor, a power source that stores power generated by natural energy such as solar power generation and wind power generation, and a power source for storing midnight electric power, and in particular, used as a power source suitable for large-power, large-current applications. In the following example, the exemplary embodiments applied to a power supply device for driving an electric vehicle will be described. 
     First Exemplary Embodiment 
     Power supply device  100  according to the first exemplary embodiment of the present invention is illustrated in  FIGS.  1  and  2   . In these figures,  FIG.  1    is an exploded perspective view of power supply device  100  according to the first exemplary embodiment, and  FIG.  2    is an exploded perspective view of power supply device  100  illustrated in  FIG.  1   . 
     Power supply device  100  illustrated in these figures includes battery stack  10  in which a plurality of battery cells  1  are stacked, a pair of end plates  20  covering both side end surfaces of battery stack  10 , a plurality of fastening members  15  that fasten end plates  20  to each other, cover assembly  40  provided on a top surface of battery stack  10 , and insulating member  30 . 
     Each of fastening members  15  is formed into a plate shape extending in a stacking direction of the plurality of battery cells  1 . Fastening members  15  are disposed on opposite side surfaces of battery stack  10 , respectively, to fasten end plates  20  to each other. 
     (Battery Stack  10 ) 
     As illustrated in  FIG.  2   , battery stack  10  includes the plurality of battery cells  1  each including positive and negative electrode terminals  2 , and bus bars connected to electrode terminals  2  of the plurality of battery cells  1  to connect the plurality of battery cells  1  in parallel and in series. The plurality of battery cells  1  are connected in parallel and in series through the bus bars. Battery cells  1  are chargeable and dischargeable secondary batteries. Power supply device  100  includes the plurality of battery cells  1  connected in parallel to form a parallel battery group, and a plurality of the parallel battery groups are connected in series to allow a number of battery cells  1  to be connected in parallel and in series. In power supply device  100  illustrated in  FIG.  2   , the plurality of battery cells  1  are stacked to form battery stack  10 . Further, the pair of end plates  20  is disposed on both end surfaces of battery stack  10 . End parts of fastening members  15  are fixed to end plates  20 , and battery cells  1  in a stacked state are fixed in a pressed state. 
     (Battery Cell  1 ) 
     As illustrated in  FIG.  2   , each of battery cells  1  is a prismatic battery having a width larger than the thickness, in other words, a prismatic battery thinner than the width, and the plurality of battery cells are stacked in a thickness to form battery stack  10 . Each of battery cells  1  can be, for example, a lithium ion secondary battery. Further, the battery cell can be any chargeable secondary battery such as a nickel metal hydride battery and a nickel cadmium battery. Battery cell  1  houses positive and negative electrode plates in outer covering can  1   a  having a sealed structure together with an electrolyte solution. Exterior can  1   a  includes a metal sheet such as aluminum or an aluminum alloy press-molded into a prismatic shape, and has an opening that is hermetically sealed with sealing plate  1   b . Sealing plate  1   b  is made of the aluminum or aluminum alloy same as prismatic outer covering can  1   a , and positive and negative electrode terminals  2  are fixed to both ends of sealing plate  1   b . Sealing plate  1   b  is provided with, between positive and negative electrode terminals  2 , gas discharge valve  1   c , which is a safety valve that opens in response to a change in pressure inside each battery cell  1 . 
     The plurality of battery cells  1  are stacked such that the thickness of each battery cell  1  aligns in the stacking direction to constitute battery stack  10 . At this time, the power of battery stack  10  can be increased by making the number of the battery cells stacked larger than usual. In such a case, battery stack  10  is long extended in the stacking direction. In battery cells  1 , terminal surfaces  1 X on which positive and negative electrode terminals  2  are provided are disposed on the same plane, and the plurality of battery cells  1  are stacked to form battery stack  10 . The top surface of battery stack  10  is a surface on which gas discharge valves  1   c  of the plurality of battery cells  1  are provided. 
     (Electrode Terminal  2 ) 
     In battery cell  1 , as illustrated in  FIG.  2    and the like, with sealing plate  1   b , which is a top surface, as terminal surface  1 X, positive and negative electrode terminals  2  are fixed to both ends of terminal surface  1 X. Electrode terminal  2  has a protrusion having a circular columnar shape. However, the protrusion is not necessarily in a circular columnar shape and may be in a polygonal columnar shape or an elliptic columnar shape. 
     Positive and negative electrode terminals  2  fixed to sealing plate  1   b  of battery cell  1  are positioned where the positive electrode and the negative electrode become bilaterally symmetrical. Consequently, as illustrated in  FIG.  2   , battery cells  1  are flipped left and right and stacked, and electrode terminals  2  of a positive electrode and a negative electrode that are adjacently close to each other are connected by a bus bar, so that adjacent battery cells  1  can be connected in series. Note that the present invention does not specify the number and connection state of the battery cells constituting the battery stack. The number and connection state of the battery cells constituting the battery stack may be modified in various manners, inclusive of other exemplary embodiments described later. 
     The plurality of battery cells  1  are stacked such that the thickness of each battery cell  1  aligns in the stacking direction to constitute battery stack  10 . In battery stack  10 , the plurality of battery cells  1  are stacked such that terminal surface  1 X provided with positive and negative electrode terminals  2  and sealing plate  1   b  in  FIG.  2    become flush with each other. 
     In battery stack  10 , insulating spacer  16  may be interposed between battery cells  1  stacked adjacently to each other. Insulating spacer  16  is made of an insulating material such as resin in the form of a thin plate or sheet. Insulating spacer  16  has a plate shape having substantially the same size as a facing surface of battery cell  1 . Insulating spacer  16  can be stacked between adjacent battery cells  1  to insulate adjacent battery cells  1  from each other. Note that, as a spacer disposed between adjacent battery cells, a spacer having a shape in which a flow path of a cooling gas is formed between the battery cell and the spacer can also be used. In addition, the surface of the battery cell can be covered with an insulating material. For example, the surface of the outer covering can excluding the electrode terminal part of the battery cell may be covered with a shrink film such as a PET resin. In this case, the insulating spacer may be omitted. Further, although a power supply device including a large number of battery cells connected in parallel and series includes an insulating spacer interposed between the battery cells connected in series to each other, no voltage difference occurs between adjacent outer covering cans in the battery cells connected in parallel to each other, and therefore the insulating spacer between these battery cells can be eliminated. 
     Furthermore, power supply device  100  illustrated in  FIG.  2    includes end plates  20  disposed on both end surfaces of battery stack  10 . Note that end surface spacer  17  may be interposed between each of end plates  20  and battery stack  10  to insulate the end plate and the battery stack from each other. End surface spacer  17  can also be produced in the form of a thin plate or sheet with an insulating material such as resin. 
     In power supply device  100  according to the first exemplary embodiment, in battery stack  10  in which the plurality of battery cells  1  are stacked on each other, electrode terminals  2  of the plurality of battery cells  1  adjacent to each other are connected by the bus bar to connect the plurality of battery cells  1  in parallel and in series. Further, a bus bar holder may be disposed between battery stack  10  and the bus bars. Use of the bus bar holder makes it possible to dispose the plurality of bus bars at fixed positions on the top surface of the battery stack while insulating the plurality of bus bars from each other and insulating the terminal surfaces of the battery cells from the bus bars. Furthermore, cover assembly  40  described later may be integrated with the bus bar holder. 
     The bus bar is manufactured into a predetermined shape by cutting and processing a metal sheet. As the metal sheet configuring the bus bar, metal that is low in electrical resistance and light in weight, such as an aluminum sheet, a copper sheet, or an alloy of these metals can be used. However, as the metal sheet for the bus bar, other metals that are low in electrical resistance and light in weight or an alloy of them can be used. 
     (End Plate  20 ) 
     As illustrated in  FIG.  2   , end plates  20  are disposed at both ends of battery stack  10  and fastened via the pair of right and left fastening members  15  disposed along both side surfaces of battery stack  10 . End plates  20  are disposed at both ends of battery stack  10  in the stacking direction of battery cells  1  and outside end surface spacers  17  to sandwich battery stack  10  from both ends. 
     (Fastening Member  15 ) 
     Each of fastening members  15  has both ends fixed to end plates  20  disposed on both end surfaces of battery stack  10 . As illustrated in  FIG.  2    and the like, fastening members  15  are each made of metal having a predetermined width and a predetermined thickness along the side surface of battery stack  10 , and are disposed to face both the side surfaces of battery stack  10 . As each of fastening members  15 , a metal sheet such as iron, preferably a steel plate can be used. Fastening member  15  made of a metal sheet is bent by press molding or the like to be formed into a predetermined shape. 
     Fastening member  15  has an upper and lower parts of plate-shaped fastening main surface  15   a  bent in a U-shape to form bent pieces  15   d . Upper and lower bent pieces  15   d  cover upper and lower surfaces of battery stack  10  from the corners on the right and left side surfaces of battery stack  10 . Fastening member  15  is fixed to outer peripheral surfaces of end plates  20  by screwing bolts  15   f  into a plurality of fastening screw holes opened in fastening main surface  15   a . Note that fastening main surface  15   a  and end plate  20  are not necessarily fixed by screwing with bolts, and may be fixed with pins, rivets, or the like. 
     Power supply device  100  in which a large number of battery cells  1  are stacked is configured to bind the plurality of battery cells  1  by connecting end plates  20  disposed at both ends of battery stack  10  including the plurality of battery cells  1  by fastening members  15 . By binding the plurality of battery cells  1  via end plates  20  and fastening members  15  having high rigidity, it is possible to suppress expansion, deformation, relative movement, malfunction due to vibration, and the like of battery cells  1  due to charging and discharging, and degradation. 
     (Cover Assembly  40 ) 
     Power supply device  100  is provided with cover assembly  40  on the top surface of battery stack  10 . Cover assembly  40  configures a gas discharge path for discharging a high-temperature, high-pressure gas to the outside of power supply device  100  when this gas is discharged from any of battery cells  1  constituting battery stack  10 . Note that cover assembly  40  may also be configured to serve as a bus bar holder that holds the bus bars. 
     (Insulating Member  30 ) 
     Further, insulating member  30  is interposed between fastening member  15  and battery stack  10 . Insulating member  30  is bent so as to cover from the side surface to a part of the bottom surface of battery stack  10 . Insulating member  30  is made of a material having insulating properties, such as a resin or the like, and insulates between fastening member  15  made of metal and the battery cells. Insulating member  30  illustrated in  FIG.  2    and the like is constituted of flat plate  31  that covers the side surface of battery stack  10 , and covering parts  32  provided above and below flat plate  31 . Flat plate  31  has a plate shape extended in the stacking direction of battery stack  10 . Each of covering parts  32  is bent from flat plate  31  to cover a part of a bottom surface of battery stack  10 . 
     Insulating member  30  is interposed between battery stack  10  and fastening member  15 , but is not necessarily in close contact with battery stack  10  or fastening member  15 . When dimensional tolerance is set in consideration of assemblability, a gap is generated between insulating member  30  and battery stack  10 . In this state, moisture contained in the air interposed in the gap may be condensed due to a temperature difference. In particular, when dew condensation water is generated between battery stack  10  and fastening member  15 , the dew condensation water is accumulated in the power supply device if the dew condensation water cannot be discharged to the outside of the power supply device. The dew condensation water accumulated in this part reaches near a top surface along a slight gap between the battery stack and the insulating member, and there is a high possibility of occurrence of so-called liquid junction in which an electrode terminal provided on the top surface of the battery cell is electrically connected to another conductive member or the like. 
     (Groove  33 ) 
     Therefore, in power supply device  100  according to the present exemplary embodiment, attention is paid to a structure for efficiently draining the generated dew condensation water to the outside of the power supply device instead of preventing the generation of the dew condensation water itself. That is, if the generated dew condensation water can be discharged faster than the speed at which the dew condensation water is generated, a risk of the liquid junction can be reduced. Here, groove  33  for discharging dew condensation water generated between battery stack  10  and fastening member  15  to the outside of the power supply device is provided in insulating member  30  with insulation interposed between the side surface of battery stack  10  and fastening member  15 . 
     Generally, a gap is not generated as long as the fastening member and the insulating member can be completely brought into close contact with each other. However, since fastening member  15  and insulating member  30  have a flat plate shape, it is difficult to completely bring the fastening member and the insulating member into close contact with each other due to dimensional tolerance and assemblability. In particular, when there is a slight gap, there is a possibility that electrode terminal  2  on the top surface is reached along insulating member  30  due to a capillary phenomenon. Therefore, in power supply device  100  according to the present exemplary embodiment, insulating member  30  is configured to promote drainage of dew condensation water by forming groove  33  in a part of a surface in contact with battery stack  10 . Since power supply device  100  according to the present exemplary embodiment has groove  33  as a path for guiding dew condensation water, it is possible to prevent electrode terminal  2  on the top surface of the battery cell from being reached through an unintended path. In particular, a width of groove  33  is preferably a width at which a capillary phenomenon occurs. Narrow groove  33  can also be expected to have an effect of sucking dew condensation water by a capillary phenomenon. For example, the width of the groove is set to 0.01 mm to 1.0 mm. Note that groove  33  is provided so as to provide a route that causes no problem even when dew condensation water is transferred, and is configured such that the induced dew condensation water is drained to the outside of the power supply device. 
     In an example illustrated in a schematic cross-sectional view of  FIG.  3   , groove  33  is formed in covering part  32 . Groove  33  is formed in a length direction of covering part  32 . As described above, in the case where insulating member  30  includes flat plate  31  and covering part  32 , the shape is bent so as to cover from the side surface to a part of the bottom surface of battery stack  10 , and dew condensation water easily accumulates in covering part  32 . However, with the configuration illustrated in  FIG.  3   , dew condensation water generated near covering part  32  can be drained to the outside of the power supply device, and dew condensation water can be prevented from accumulating in covering part  32 . Accordingly, it is possible to suppress a situation in which dew condensation water accumulated in the vicinity of covering part  32  is sucked up by the gap between the side surface of the battery stack and insulating member  30  and is propagated near the top surface of battery cell  1 . As a result, it is possible to avoid a situation in which electrode terminal  2  provided on the top surface of battery cell  1  is liquid-connected to another conductive part due to dew condensation water. 
     Second Exemplary Embodiment 
     In the present invention, uneven groove shape  35  is not limited to the configuration of  FIG.  3   . For example, in power supply device  200  according to a second exemplary embodiment, as illustrated in a schematic cross-sectional view of  FIG.  4   , the groove shape formed in covering part  32 B instead of flat plate  31 B of insulating member  30 B is uneven in which step  35 B is formed toward an opening surface. Forming the unevenness stepwise in this manner makes it possible to secure a space for storing dew condensation water at a position separated from a gap between the side surface of the battery stack and insulating member  30 , and to more effectively prevent suction of dew condensation water due to a capillary phenomenon between the side surface of the battery stack and insulating member  30 . 
     Third Exemplary Embodiment 
     Further, the unevenness is not limited to the configuration formed horizontally, and may be inclined. For example, it may be formed in a linear shape inclined with respect to an extending direction of flat plate  31 . As a result, a downward gradient is formed, and dew condensation water can be guided in a direction defined by the downward gradient and can be safely discharged from the power supply device. For example, in power supply device  300  according to a third exemplary embodiment, as illustrated in a schematic cross-sectional perspective view of  FIG.  5   , uneven groove shape  35 C formed in covering part  32 C instead of flat plate  31 C of insulating member  30 C is formed to have a downward gradient in a right direction in the drawing. As a result, it is possible to discharge the accumulated dew condensation water from insulating member  30  along the downward gradient of groove shape  35   c  while preventing the crawling up due to the capillary phenomenon by groove shape  35 C. 
     Fourth Exemplary Embodiment 
     Although an example in which groove  33  is provided in covering part  32  has been described in the above examples, the present invention does not limit a part where the capillary phenomenon blocking structure is provided to the covering part, and the groove can be provided at any position on the path where the dew condensation water may cause unintended conduction due to the capillary phenomenon. For example, in power supply device  400  according to a fourth exemplary embodiment, as illustrated in a schematic sectional view of  FIG.  6   , groove shape  35 D is provided as the capillary phenomenon blocking structure in a part of flat plate  31 D instead of covering part  32 D of insulating member  30 D. This prevents dew condensation water from flowing along flat plate  31 D and climbing up the side surface of battery stack  10 . 
     Groove shape  35  is preferably provided below flat plate  31 . As a result, the crawling up of the dew condensation water is suppressed below flat plate  31 , the diffusion of the dew condensation water is suppressed, and the safety is further enhanced. 
     Fifth Exemplary Embodiment 
     As described above, the inclined surface can be formed in the capillary phenomenon blocking structure such as the unevenness. Here, the inclined surface is not limited to one that is linearly inclined in one direction, and a plurality of inclined surfaces may be provided. For example, as power supply device  500  according to a fifth exemplary embodiment, in insulating member  30 E illustrated in a schematic cross-sectional view of  FIG.  7   , not covering part  32 E but flat plate  31 E is provided with groove shape  35 E having an inclined surface with a downward gradient to the left and right in a mountain shape. As a result, the dew condensation water can be discharged to the left and right of insulating member  30 E in the drawing, and more smooth discharge can be expected by shortening a path length for discharge. 
     Sixth Exemplary Embodiment 
     Further, the groove is not limited to a configuration in which the groove is extended with a constant width, and a partially wide part may be provided. For example, in an example illustrated in a schematic cross-sectional view of  FIG.  8    as power supply device  700  according to a seventh exemplary embodiment, in covering part  32 G of insulating member  30 G, groove shape  35 G is formed so as to expand in a discharge direction. Accordingly, dew condensation water can be more easily discharged from a gap between flat plate  31 G of insulating member  30 G and the battery stack. 
     Further, insulating member  30  may form a water-repellent film on a part or the entire surface thereof. Generally, the capillary phenomenon is considered to have a large influence when the liquid wets a tube, that is, when an adhesion force is large, and thus the capillary phenomenon can be suppressed by enhancing the water repellency. 
     With such a configuration, even in a case where a drainage path for draining dew condensation water is small, for example, even in a case where a depth of the groove is low and a width is narrow, the speed of draining can be promoted. Further, since the water can be efficiently drained, the power supply device can be downsized. Furthermore, when a certain amount of dew condensation water is accumulated due to surface tension, the dew condensation water cannot be discharged and stays inside the power supply device in some cases. On the other hand, discharge can be promoted by using the capillary phenomenon, and it is possible to obtain an advantage that the dew condensation water can be discharged early from a state where the amount of dew condensation water is small. 
     Power supply device  100  described above can be used as a power source for a vehicle that supplies electric power to a motor that causes an electric vehicle to travel. As an electric vehicle equipped with power supply device  100 , electric vehicles such as a hybrid automobile and a plug-in hybrid automobile that travel with both an engine and a motor, or an electric automobile that travels only with a motor can be used, and the power supply device is used as a power source for these vehicles. Note that an example will be described in which a large-capacity, high-output power supply device where a large number of power supply devices  100  described above are connected in series or in parallel in order to obtain electric power for driving an electric vehicle and a necessary controlling circuit is further added is constructed. 
     (Power Supply Device for Hybrid Automobile) 
       FIG.  9    illustrates an example in which power supply device  100  is mounted on a hybrid automobile that travels by both an engine and a motor. Vehicle HV on which power supply device  100  illustrated in this drawing is mounted includes vehicle body  91 , engine  96  and motor  93  for traveling that cause vehicle body  91  to travel, wheels  97  that are driven by engine  96  and motor  93  for traveling, power supply device  100  that supplies electric power to motor  93 , and power generator  94  that charges a battery of power supply device  100 . Power supply device  100  is connected to motor  93  and power generator  94  via DC/AC inverter  95 . Vehicle HV travels by both motor  93  and engine  96  while charging and discharging the battery of power supply device  100 . Motor  93  is driven in a region where engine efficiency is low, for example, during acceleration or low-speed traveling, and causes the vehicle to travel. Motor  93  is driven by electric power supplied from power supply device  100 . Power generator  94  is driven by engine  96  or by regenerative braking generated at the time of applying braking to the vehicle, and charges the battery of power supply device  100 . Note that, as illustrated in  FIG.  9   , vehicle HV may include charging plug  98  for charging power supply device  100 . By connecting charging plug  98  to an external power source, power supply device  100  can be charged. 
     (Power Supply Device for Electric Automobile) 
       FIG.  10    illustrates an example in which power supply device  100  is mounted on an electric automobile that travels only by a motor. Vehicle EV on which power supply device  100  illustrated in this drawing is mounted includes vehicle body  91 , motor  93  for traveling that causes vehicle body  91  to travel, wheels  97  that are driven by motor  93 , power supply device  100  that supplies electric power to motor  93 , and power generator  94  that charges a battery of power supply device  100 . Power supply device  100  is connected to motor  93  and power generator  94  via DC/AC inverter  95 . Motor  93  is driven by electric power supplied from power supply device  100 . Power generator  94  is driven by an energy at the time of applying regenerative braking to vehicle EV and charges the battery of power supply device  100 . Further, vehicle EV includes charging plug  98 , and power supply device  100  can be charged by connecting charging plug  98  to an external power source. 
     (Power Supply Device for Power Storage Device) 
     Further, the present invention does not limit the application of the power supply device to a power source for a motor that causes a vehicle to travel. The power supply device according to the exemplary embodiment can be used also as a power source for a power storage device that charges a battery with electric power generated by solar power generation, wind power generation, or the like, and stores electricity.  FIG.  11    illustrates a power storage device that charges a battery of power supply device  100  with solar battery  82  and stores electricity. 
     The power storage device illustrated in  FIG.  11    charges the battery of power supply device  100  with electric power generated by solar battery  82  disposed on a roof, a rooftop, or the like of building  81  such as a house or a factory. In this power storage device, the battery of power supply device  100  is charged by charging circuit  83  using solar battery  82  as a charging power source, and thereafter, electric power is supplied to load  86  via DC/AC inverter  85 . Therefore, the power storage device includes a charge mode and a discharge mode. In the power storage device illustrated in the figure, DC/AC inverter  85  is connected to power supply device  100  via discharging switch  87 , and charging circuit  83  is connected to power supply device  100  via charging switch  84 . Discharging switch  87  and charging switch  84  are turned on and off by power supply controller  88  of the power storage device. In the charge mode, power supply controller  88  turns on charging switch  84  and turns off discharging switch  87  to allow charging from charging circuit  83  to power supply device  100 . Further, when charging is completed and the battery is fully charged or when the battery is in a state where a capacity of a predetermined value or more is charged, power supply controller  88  turns off charging switch  84  and turns on discharging switch  87  to switch the mode to the discharge mode and allows discharging from power supply device  100  to load  86 . Furthermore, when necessary, the power supply controller can turn on charging switch  84  and turn on discharging switch  87  to supply electricity to load  86  and charge power supply device  100  simultaneously. 
     Further, although not illustrated, the power supply device can be used as a power source for a power storage device that stores electricity by charging a battery using midnight electric power at nighttime. The power supply device that is charged with midnight electric power is charged with the midnight electric power that is surplus electric power generated by a power station, and outputs the electric power during the daytime when an electric power load increases, which can limit peak electric power during the daytime to a small value. Furthermore, the power supply device can also be used as a power source charged with both an output of a solar battery and midnight electric power. This power supply device can effectively utilize both electric power generated by the solar battery and the midnight electric power, and can efficiently store power in consideration of weather and power consumption. 
     The power storage system as described above can be suitably used in applications such as a backup power supply device that can be installed in a computer server rack, a backup power supply device for radio base stations for cellular phones and the like, a power storage device combined with a solar battery such as a power storage power source for homes and factories or a power source for street lights, and a backup power source for traffic lights and traffic indicators on roads. 
     INDUSTRIAL APPLICABILITY 
     The power supply device according to the present invention, and a vehicle and a power storage device including the power supply device can be suitably used as a power source for a large current, which is used for a power source of a motor for driving an electrically-driven vehicle such as a hybrid automobile, a fuel cell automobile, an electric automobile, or an electric motorcycle. Examples include a power supply device for a plug-in hybrid electric automobile and a hybrid electric automobile that can switch between an EV travelling mode and an HEV travelling mode, an electric automobile, and the like. Further, the present invention can be appropriately used for applications such as a backup power supply device that can be mounted on a rack of a computer server, a backup power supply device for a radio base station such as a cellular phone, a power source for power storage for home and factory use, a power source for street lamps, and the like, a power storage device combined with a solar battery, and a backup power source for traffic lights and the like. 
     REFERENCE MARKS IN THE DRAWINGS 
     
         
           100 ,  200 ,  300 ,  400 ,  500 ,  700 : power supply device 
           1 : battery cell 
           1 X: terminal surface 
           1   a : outer covering can 
           1   b : sealing plate 
           1   c : gas discharge valve 
           2 : electrode terminal 
           10 : battery stack 
           15 : fastening member 
           15   a : fastening main surface 
           15   d : bent piece 
           15   f : bolt 
           16 : insulating spacer 
           17 : end surface spacer 
           20 : end plate 
           30 ,  30 B,  30 C,  30 D,  30 E,  30 G: insulating member 
           31 ,  31 B,  31 C,  31 D,  31 E,  31 G: flat plate 
           32 ,  32 B,  32 C,  32 D,  32 E,  32 G: covering part 
           33 : groove 
           35 ,  35 C,  35 D,  35 E,  35 G: groove shape 
           36 : step 
           40 : cover assembly 
           81 : building 
           82 : solar battery 
           83 : charging circuit 
           84 : charging switch 
           85 : DC/AC inverter 
           86 : load 
           87 : discharging switch 
           88 : power supply controller 
           91 : vehicle body 
           93 : motor 
           94 : power generator 
           95 : DC/AC inverter 
           96 : engine 
           97 : wheel 
           98 : charging plug 
         HV, EV: vehicle