Patent Publication Number: US-2023155228-A1

Title: Battery module

Description:
This nonprovisional application is based on Japanese Patent Application No. 2021-187142 filed on Nov. 17, 2021 with the Japan Patent Office, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present technology relates to a battery module. 
     Description of the Background Art 
     A battery module in which a plurality of battery cells are stacked has been conventionally known, A partition wall portion (separator) for securing insulation is provided between the plurality of battery cells, and a path for cooling air is provided in the partition wall portion (Japanese Patent Laying-Open No. 2010-61982 and Japanese Patent Laying-Open No. 2004-362879). 
     SUMMARY OF THE INVENTION 
     For further reduction of manufacturing cost, however, there is still room for improvement in the cooling structure of the battery module. It is an object of the present technology to provide a battery module to attain efficient cooling while reducing manufacturing cost. 
     A battery module according to the present technology includes: a plurality of battery cells arranged side by side in a first direction, each of the plurality of battery cells having a prismatic shape; and a partition wall portion provided between the plurality of battery cells to secure electrical insulation between the plurality of battery cells. The partition wall portion includes a first partition wall portion and a second partition wall portion, the first partition wall portion and the second partition wall portion being provided alternately, the second partition wall portion having a shape different from a shape of the first partition wall portion, the second partition wall portion forming a cooling space between the second partition wall portion and each of two battery cells located on both sides beside the second partition wall portion in the first direction. 
     The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view showing a configuration of a battery module according, to one embodiment of the present technology. 
         FIG.  2    is a perspective view of the battery module of  FIG.  1    when viewed in a direction of an arrow II. 
         FIG.  3    is a perspective view showing configurations of a unit and end plates included in the battery module according to the embodiment of the present technology. 
         FIG.  4    is a perspective view showing a configuration of the unit included in the battery module according to the embodiment of the present technology. 
         FIG.  5    is a cross sectional view of the unit of  FIG.  4    when viewed in a direction of an arrow V. 
         FIG.  6    is a perspective view showing a configuration of a battery cell included in the battery module according to the embodiment of the present technology. 
         FIG.  7    is a partial perspective view showing a configuration of each voltage detection wire included in the battery module according to the embodiment of the present technology. 
         FIG.  8    is a cross sectional view of the unit of  FIG.  4    when viewed in a direction of arrows of a line VIII-VIII. 
         FIG.  9    is an enlarged view of a portion IX in  FIG.  8   . 
         FIG.  10    is a cross sectional view when viewed in a direction of arrows of a line X-X in  FIG.  8   . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, embodiments of the present technology will be described. It should be noted that the same or corresponding portions are denoted by the same reference characters, and may not be described repeatedly. 
     It should be noted that in the embodiments described below, when reference is made to number, amount, and the like, the scope of the present technology is not necessarily limited to the number, amount, and the like unless otherwise stated particularly. Further, in the embodiments described below, each component is not necessarily essential to the present technology unless otherwise stated particularly. 
     It should be noted that in the present specification, the terms “comprise”, “include”, and “have” are open-end terms. That is, when a certain configuration is included, a configuration other than the foregoing configuration may or may not be included. Further, the present technology is not limited to one that necessarily exhibits all the functions and effects stated in the present embodiment. 
     In the present specification, the term “battery” is not limited to a lithium ion battery, and may include another battery such as a nickel-metal hydride battery. In the present specification, the term “electrode” may collectively represent a positive electrode and a negative electrode. Further, the term “electrode plate” may collectively represent a positive electrode plate and a negative electrode plate. 
     It should be noted that in the figures, a stacking direction of the battery cells is defined as a first direction serving as a Y direction, a direction in which two electrode terminals of each battery cell are arranged side by side is defined as a second direction serving as an X direction, and a height direction of the battery cell is defined as a third direction serving as a Z direction. 
       FIG.  1    is a perspective view showing a configuration of a battery module according to one embodiment of the present technology.  FIG.  2    is a perspective view of the battery module of  FIG.  1    when viewed in a direction of an arrow H.  FIG.  3    is a perspective view showing configurations of a unit and end plates included in the battery module according to the embodiment of the present technology. 
     A battery module  1  is used as a power supply for driving a vehicle such as a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), or a battery electric vehicle (BEV), for example. 
     First, an overall structure of battery module  1  will be described. As shown in  FIGS.  1  to  3   , battery module  1  includes a plurality of units  10 , end plates  400 , restraint members  500 , a lower restraint member  550 , a wiring member  600 , a duct  700 , and connection terminals  800 . 
     The plurality of units  10  are arranged side by side in the first direction (Y direction). Six units  10  are arranged side by side in the Y direction as the plurality of units  10  according to the present embodiment. It should be noted that the number of the plurality of units  10  is not particularly limited as long as two or more units  10  are included. 
     The plurality of units  10  are sandwiched between two end plates  400 . The plurality of units  10  according to the present embodiment are pressed by end plates  400  and restrained between two end plates  400 . 
     End plates  400  are provided at the both ends beside the plurality of units  10  in the Y direction. Each of end plates  400  is fixed to a base such as a pack case that accommodates battery module  1 . End plate  400  is composed of, for example, aluminum or iron. 
     Restraint members  500  are provided on both sides beside the plurality of units  10  and end plates  400  in the X direction. When restraint members  500  are engaged with end plates  400  with compressive force in the Y direction being applied to the plurality of units  10  arranged side by side and to end plates  400  and then the compressive force is released, tensile force acts on restraint members  500  that connect two end plates  400 . As a reaction thereto, restraint members  500  press two end plates  400  in directions of bringing them closer to each other. As a result, restraint members  500  restrain the plurality of units  10  in the first direction (the Y direction). 
     Each of restraint members  500  includes a plate-shaped portion  510 , a first flange portion  520 , and second flange portions  530 . Restraint member  500  is composed of iron, for example. 
     Plate-shaped portion  510  is a member extending in the Y direction. Plate-shaped portion  510  is provided with a plurality of openings  511 . The plurality of openings  511  are provided at intervals m the Y direction, and each of openings  511  is constituted of a through hole extending through plate-shaped portion  510  in the X direction. 
     First flange portion  520  extends from beside the side surfaces of the plurality of units  10  so as to be located over the upper surfaces of the plurality of units  10 . By providing first flange portion  520 , rigidity of restraint member  500  formed to be relatively thin can be secured. 
     Second flange portions  530  are connected to both ends of plate-shaped portion  510  in the Y direction. Second flange portions  530  are fixed to end plates  400 . Second flange portions  530  are fixed to end plates  400  by a known fixing method such as fastening of bolt, for example. Thus, restraint members  500  connect two end plates  400  to each other. 
     As shown in  FIG.  2   , lower restraint member  550  is provided on the bottom surfaces of the plurality of units  10  and end plates  400 . Lower restraint member  550  protects below-described battery cells  100  from the bottom surface side. Lower restraint member  550  is composed of iron, for example. 
     As shown in  FIG.  1   , wiring member  600  is provided at a position facing the plurality of units  10  in the Z direction. Wiring member  600  extends in the Y direction through the center portion of each of the plurality of units  10  in the X direction. Wiring member  600  is electrically connected to the plurality of units  10 . Wiring member  600  is, for example, a flexible printed circuit board. 
     Duct  700  extends in the Y direction. Duct  700  extends at a position overlapping with wiring member  600  when viewed in the Z direction Duct  700  is disposed between each of the plurality of units  10  and wiring member  600  in the Z direction. 
     Connection terminals  800  are arranged on both sides beside the plurality of units  10  arranged side by side in the Y direction. Each of connection terminals  800  is provided at a position overlapping with end plate  400  when viewed in the Z direction. Connection terminal  800  connects battery module  1  to an external wiring such as a cable (not shown) disposed outside battery module  1 . 
     Next, a structure of unit  10  will be described.  FIG.  4    is a perspective view showing a configuration of the unit included in the battery module according to the embodiment of the present technology.  FIG.  5    is a perspective view of the unit of  FIG.  4    when viewed in a direction of an arrow V. 
     As shown in  FIGS.  4  and  5   , each of the plurality of units  10  includes a plurality of battery cells  100 , a case  200  serving as a supporting member, and a bus bar  300 . 
     Unit  10  includes two or more battery cells  100 . Unit  10  according to one embodiment of the present technology includes four battery cells  100  as an even number of battery cells  100 . It should be noted that the number of battery cells  100  included in each of the plurality of units  10  is not particularly limited as long as two or more battery cells  100  are included. Moreover, an odd number of battery cells  100  may be included in each of the plurality of units  10 . 
     The plurality of battery cells  100  are arranged side by side in the first direction (Y direction). Four battery cells  100  are arranged side by side in the Y direction as the plurality of battery cells  100  according to the embodiment of the present technology. The arrangement direction of the plurality of units  10  is the same as the arrangement direction of the plurality of battery cells  100  in each of the plurality of units  10 . 
     Case  200  has an external appearance with a rectangular parallelepiped shape. Case  200  accommodates the plurality of battery cells  100 . Case  200  is composed of, for example, a resin such as polypropylene. As shown in  FIGS.  1  to  3   , case  200  is compressed in the first direction (V direction) by restraint members  500 . 
     As shown in  FIGS.  4  and  5   , case  200  has a front wall portion  210 , a rear wall portion  220 , a first side wall portion  230 , a second side wall portion  240 , and an upper surface portion  250 . 
     Front wall portion  210  is a surface adjacent to one of restraint members  500 , As shown in  FIG.  4   , front wall portion  210  is provided with a plurality of first ventilation ports  211 . Each of first ventilation ports  211  is a through hole extending through front wall portion  210  in the X direction. 
     As shown in  FIG.  5   , rear wall portion  220  is a surface facing front wall portion  210  with the plurality of battery cells  100  being interposed therebetween in the X direction. Rear wall portion  220  is provided with a plurality of second ventilation ports  221 . Each of second ventilation ports  221  is a through hole extending through rear wall portion  220  in the X direction, Each of the plurality of second ventilation ports  221  communicates, through a below-described communication space  280 , with a corresponding one of first ventilation ports  211  arranged side by side in the X direction. 
     First side wall portion  230  and second side wall portion  240  are arranged side by side in the first direction (Y direction), and face each other. 
     As shown in  FIG.  4   , first side wall portion  230  has a protrusion  231 . Protrusion  231  protrudes opposite to second side wall portion  240 . As shown in  FIG.  5   , second side wall portion  240  is provided with a recess  241 . Recess  241  is recessed toward first side wall portion  230  and has a shape engageable with protrusion  231 . Protrusion  231  and recess  241  of adjacent units  10  of the plurality of units  10  are engaged with each other. 
     Upper surface portion  250  includes first wall portions  251 , second wall portions  252 , third wall portions  253 , fourth wall portions  254 , engagement surfaces  255 , and hole portions  256 . Two first wall portions  251  are formed parallel to each other so as to extend in the Y axis direction at the center portion in the X direction. Second wall portions  252 , third wall portions  253 , and fourth wall portions  254  are provided on both sides beside first wall portions  251  in the X direction so as to define installation positions for bus bars  300  Each of second wall portions  252  is provided with a notch  252 A through which a below-described voltage detection wire  610  extends. Second flange portions  530  of restraint members  500  are engaged with engagement surfaces  255 . Hole portions  256  communicate with below-described gas-discharge valves  130 . 
     Each of bus bars  300  is composed of an electric conductor. The plurality of bus bars  300  electrically connect the plurality of battery cells  100  together. 
       FIG.  6    is a perspective view showing a configuration of a battery cell included in the battery module according to the embodiment of the present technology. 
     As shown in  FIG.  6   , battery cell  100  is, for example, a lithium ion battery. Battery cell  100  has a prismatic shape. Individual battery cell  100  has an output density of, for example, about 8000 W/L or more. 
     Battery cell  100  according to the present embodiment has electrode terminals  110 , a housing  120 , and a gas-discharge valve  130 . 
     Electrode terminals  110  are formed on housing  120 . Electrode terminals  110  have a positive electrode terminal  111  and a negative electrode terminal  112  as two electrode terminals  110  arranged side by side along the second direction (the X direction) orthogonal to the first direction (the Y direction). 
     Positive electrode terminal  111  and negative electrode terminal  112  are provided to be separated from each other in the X direction. Positive electrode terminal  111  and negative electrode terminal  112  are provided on both sides beside wiring member  600  and duct  700  in the X direction. 
     Housing  120  has a rectangular parallelepiped shape, and forms the external appearance of battery cell  100 . An electrode assembly (not shown) and an electrolyte solution (not shown) are accommodated in housing  120 . 
     Housing  120  includes an upper surface  121 , a lower surface  122 , a first side surface  123 , a second side surface  124 , and a third side surface  125 . 
     Upper surface  121  is a flat surface orthogonal to the Z direction. Electrode terminals  110  are disposed on upper surface  121 . Lower surface  122  faces upper surface  121  along the third direction (Z direction) orthogonal to the first direction (Y direction). 
     Each of first side surface  123  and second side surface  124  is constituted of a flat surface orthogonal to the Y direction. Each of first side surface  123  and second side surface  124  has the largest area among the areas of the plurality of side surfaces of housing  120 . Each of first side surface  123  and second side surface  124  has a rectangular shape when viewed in the Y direction. Each of first side surface  123  and second side surface  124  has a rectangular shape in which the X direction corresponds to the long-side direction and the Z direction corresponds to the short-side direction when viewed in the Y direction. 
     The plurality of battery cells  100  are stacked such that first side surfaces  123  of battery cells  100 ,  100  adjacent to each other in the Y direction face each other and second side surfaces  124  of battery cells  100 ,  100  adjacent to each other in the Y direction face each other. Thus, positive electrode terminals  111  and negative electrode terminals  112  are alternately arranged in the Y direction in which the plurality of battery cells  100  are stacked. 
     It should be noted that when an odd number of battery cells  100  are included in unit  10 , the posture of unit  10  may be turned by 180° with respect to the Z axis between units  10  adjacent to each other in the direction. 
     Gas-discharge valve  130  is provided in upper surface  121 . When internal pressure of housing  120  becomes more than or equal to a predetermined value due to gas generated inside housing  120 , gas-discharge valve  130  discharges the gas to the outside of housing  120 . The gas from gas-discharge valve  130  flows through duct  700  in  FIG.  1    and is discharged to the outside of battery module  1 . 
       FIG.  7    is a partial perspective view showing a configuration of each voltage detection wire included in the battery module according to the embodiment of the present technology. 
     As shown in  FIG.  7   , wiring member  600  includes voltage detection wires  610  that each detects a voltage. The plurality of voltage detection wires  610  extend to and are connected to bus bars  300 . One voltage detection wire  610  is disposed in each of the plurality of units  10 . Thus, voltage detection wire  610  can detect the voltage of unit  10 . 
       FIG.  8    is a cross sectional view of the unit of  FIG.  4    when viewed in a direction of arrows of a line VIII-VIII.  FIG.  9    is an enlarged view of a portion TX in  FIG.  8   .  FIG.  10    is a cross sectional view when viewed in a direction of arrows of a line X-X in  FIG.  8   . 
     As shown in  FIGS.  8  to  10   , case  200  serving as a supporting member further has partition wall portions. Each of the partition wall portions is located between the plurality of battery cells  100 , and functions as a separator to secure electrical insulation between the plurality of battery cells  100 . The partition wall portions according to the present embodiment have a first partition wall portion  260  and second partition wall portions  270 . 
     As shown in  FIG.  8   , battery cells  100  are sandwiched by first partition wall portion  260  and second partition wall portions  270  of case  200 . Case  200  supports battery cells  100  in the first direction (Y direction). 
     First partition wall portion  260  is located at substantially the center of unit  10  in the Y direction. First partition wall portion  260  in the present embodiment is disposed between two battery cells  100  arranged on the center side in the Y direction among four battery cells  100  accommodated in unit  10 . First partition wall portion  260  is continuous in the Z direction inside case  200 . 
     Second partition wall portions  270  are provided on both sides beside first partition wall portion  260  in the Y direction with battery cells  100  being interposed therebetween. Second partition wall portions  270  are continuous in the Z direction inside case  200 . 
     Each of second partition wall portions  270  has thin portions  271  and ribs  272 . Each of thin portions  271  is a portion of second partition wall portion  270  with a small thickness in the Y direction. Four thin portions  271  are provided along the Z direction so as to be centered on the upper surface portion  250  side with respect to the center of second partition wall portion  270  in the Z direction. Ribs  272  are located among four thin portions  271 . 
     In battery module  1 , first partition wall portion  260  and second partition wall portion  270  are alternately arranged side by side in the first direction (Y direction). First partition wall portion  260  and second partition wall portion  270  have different shapes. Each of first partition wall portion  260  and second partition wall portion  270  is in abutment with battery cell  100  in the first direction (Y direction). On this occasion, a contact area (second area) between second partition wall portion  270  and battery cell  100  is smaller than a contact surface (first area) between first partition wall portion  260  and battery cell  100 . 
     A partition wall portion is provided with a communication space  280  (cooling space) extending in the second direction (X direction) intersecting the first direction (Y direction) and the third direction (Z direction). Regarding the partition wall portions according to the present embodiment, a plurality of communication spaces  280  are provided in the both surfaces of second partition wall portion  270 . Since thin portions  271  and ribs  272  are formed in second partition wall portions  270 , communication spaces  280  communicate inside case  200  in which battery cells  100  are accommodated. Communication spaces  280  communicate with first ventilation ports  211  and second ventilation ports  221 . 
     As shown in  FIG.  10   , communication space  280  is formed to extend across a whole of a width direction of second partition wall portion  270  in the second direction (X direction). Communication spaces  280  are continuous to openings  511  in the second direction (X direction). Thus, by introducing cooling air from first ventilation ports  211  or second ventilation ports  221  and allowing the cooling air to flow through communication spaces  280 , battery cells  100  accommodated in case  200  can be cooled. 
     At least part of communication spaces  280  is located on the upper surface  121  side with respect to the center between upper surface  121  and lower surface  122  of housing  120 . In the embodiment of the present technology, two communication spaces  281 ,  282  provided on the upper surface  121  side among four communication spaces  281 ,  282 ,  283 ,  284  arranged side by side in the Z direction are located on the upper surface  121  side with respect to the center between upper surface  121  and lower surface  122 . 
     Since at least part of communication spaces  280  is located on the upper surface  121  side with respect to the center between upper surface  121  and lower surface  122 , the center of gravity of case  200  serving as a supporting member can be low, with the result that case  200  can be stably freestanding. 
     In battery module  1  according to the embodiment of the present technology, second partition wall portions  270 , each of which has both surfaces provided with communication spaces  280  that contribute to cooling of battery cell  100 , are provided at every other location along the first direction (V direction), thereby providing the same cooling effect to all the battery cells  100 . On the other hand, the thickness of first partition wall portion  260  having no communication space  280  formed therein can be made smaller than that of second partition wall portion  270 . Therefore, battery cells  100  can be efficiently and uniformly cooled while attaining reduced manufacturing cost and reduced size of battery module  1 . 
     Further, in battery module  1 , since the plurality of battery cells  100  are accommodated in case  200  such that they are arranged side by side in the first direction (Y direction), unit  10  is formed, and the plurality of such units  10  are arranged side by side in the first direction (Y direction) to form battery module  1 , the manufacturing process can be simplified as compared with a case where battery module  1  is manufactured with each of the plurality of battery cells  100  being handled as one unit. An example of the simplification is, for example, as follows: units  10  each formed to be small is caused to pass through a welding machine to weld bus bars  300  in units  10 , and then bus bars  300  over different units  10  are individually joined together, thereby attaining increased efficiency in the welding process. 
     Further, in battery module  1 , since units  10  each including the plurality of battery cells  100  accommodated in case  200  are formed, battery module  1  can be readily disassembled or replaced with each unit  10  being handled as one unit. 
     Further, in battery module  1 , since units  10  each including the plurality of battery cells  100  accommodated in case  200  are formed, battery module  1  can be divided with each unit  10  being handled as one unit when discarding battery module  1  so as to lower the voltage for the purpose of handling, thereby facilitating the discarding of battery module  1 . 
     Further, in battery module  1 , battery cells  100  can be restrained by restraint members  500  through the configurations of units  10 . 
     Further, in battery module  1 , the plurality of units  10  are connected together by bus bars  300 , with the result that battery module  1  can be manufactured with unit  10  being handled as one unit. 
     Further, in battery module  1 , since one voltage detection wire  610  is disposed on one unit  10 , cost of battery module  1  can be low as compared with a case where voltage detection wire  610  is disposed on each of battery cells  100 . 
     Further, in battery module  1 , two or more battery cells  100  are included in one unit and each of two or more battery cells  100  is set to have an output density of about 8000 W/L or more, thereby forming a power supply device having a predetermined voltage or more with each of the units being handled as one unit. 
     Although the embodiments of the present invention have been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the scope of the present invention being interpreted by the terms of the appended claims. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.