JP2015076188A - Battery module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery module that is able to improve the face pressure distribution of a restricted face, is able to prevent a battery performance decrease, and is able to reduce the weight of a module case.SOLUTION: A battery module comprises: a cell laminate 4 formed from a plurality of flat cells 3; and a restricting structure that presses and restricts the cell laminate 4. The restricting structure has a pressing plate 2, a deformation plate 6, and an end plate 5. The pressing plate 2 presses the cell laminate 4 in its thickness direction. The deformation plate 6 is welded to the pressing plate 2 by first and second weld parts W11, W12. The end plate 5 is welded to the deformation plate 6 by second weld parts W21, W22, deforms the deformation plate 6 with forces indicated by arrows Y11, Y12, and presses the pressing plate 2 against the cell laminate 4. The first weld parts W11, W12 are located on the outer circumferential edge side of the pressing plate 2 with respect to the second weld parts W21, W22.

Description

  The present invention relates to a battery stack formed by laminating a plurality of flat batteries formed by sealing a power generation element inside a sheet-shaped outer package in the thickness direction of the flat battery, and the thickness of the battery stack. The present invention relates to a battery module including a restraining structure that restrains by pressing in a direction.

  Conventionally, a battery pack described in Patent Document 1 is known. This battery pack is configured by installing a plurality of battery modules each containing a battery stack in which secondary batteries constituting unit batteries are stacked. In Patent Document 1, in the battery pack, each unit battery constituting the battery module can be appropriately pressurized, and when each unit battery bulges in the battery module, the stress due to the bulge is applied. A battery pack configuration that can absorb well is provided.

  For this reason, the battery pack of Patent Document 1 includes a plurality of battery modules each including a battery stack in which a plurality of unit cells are stacked and a storage case that stores the battery stack. And the storage case which comprises a battery module has the convex part formed along the outer periphery of a storage case. This convex part exists in the position which presses the center part of a battery laminated body. A bulging portion (described as a concave portion) is provided at the center of the battery stack so that a convex portion facing the convex portion is formed. Accordingly, when the battery stack is tightened by providing bolts on the upper and lower portions of the storage case, the central portion of the battery stack is pressed by the convex portion and the bulging portion.

JP 2012-119232 A

  According to the technique disclosed in Patent Document 1, the central portion of the flat battery is pressed when the flat battery constituting the unit battery is expanded, but the end portion of the flat battery is not pressed. As a result, the constraining surface of the flat battery has a pressed portion and a non-pressed portion, and an undesired surface pressure distribution of the constraining surface occurs, and metal lithium is precipitated due to local current concentration. There is a problem that deterioration such as the above occurs.

  Moreover, due to an unfavorable surface pressure distribution on the constraining surface, a gas is generated inside each flat battery during charging and discharging, and if this gas stays between the electrode plates of the power generation element, the performance of the battery decreases. Furthermore, the end plate of the battery pack of Patent Document 1 needs to be thick so as not to be deformed, which increases the weight.

  In view of the above problems, an object of the present invention is to provide a battery module that can suppress an undesirable surface pressure distribution of a constraining surface in a constraining structure and prevent deterioration in battery performance.

  Descriptions of patent documents listed as prior art can be introduced or incorporated by reference as explanations of technical elements described in this specification.

  In order to achieve the above object, the present invention employs the following technical means. That is, according to one aspect of the present invention, a battery module includes a plurality of flat batteries (3) in which a power generation element is sealed inside a sheet-shaped outer package in the thickness direction of the flat battery (3). Thus, the battery stack (4) is configured. Moreover, the battery module is provided with the restraint structure which presses and restrains a battery laminated body (4) in the thickness direction. The restraint structure includes a pressing plate (2) that presses the battery stack (4) in the thickness direction, and a deformation plate (6) welded to the pressing plate (2) by the first welded portion (W11, W12). ) And an end plate (5).

  The end plate (5) is welded to the deformation plate (6) by the second welded portion (W21, W22), deforms the deformation plate (6), and presses the pressing plate (2) against the battery stack (4). . Further, a pressing plate (2) is provided between the deformation plate (6) and the battery stack (4), and the first welded portion (W11, W12) is pressed more than the second welded portion (W21, W22). It is located on the outer peripheral edge side of the plate (2).

  According to this invention, the entire surface to be restrained of the flat battery constituting the battery stack can be pressed, and unevenness of the surface pressure distribution during pressing can be suppressed. Therefore, when the flat battery is swollen, the stress due to the swollenness can be absorbed better. Since unevenness of the surface pressure distribution can be suppressed, generation of gas in each flat battery during charging / discharging can be suppressed, and deterioration in battery performance due to the gas staying between the electrode plates of the power generation element can be suppressed.

  Next, in one aspect of the present invention, when the outer peripheral edge side of the end plate (5) is pressed in the thickness direction, the portion of the deformation plate (6) adjacent to the second welded portion (W21, W22) and the pressing plate A gap (G1) is formed between (2) and (2).

  According to this invention, the gap which is larger than that before pressing is formed between the pressing plate and the deformation plate adjacent to the second welding portion, so that the first welding portion located on the outer peripheral edge side of the pressing plate is formed. The pressure applied is stronger than the pressing force, and unevenness of the surface pressure distribution is suppressed.

  Next, in one of the present invention, the deformation plate (6) is more easily deformed than the end plate (5) and the pressing plate (2).

  According to this invention, the deformation plate is easily deformed when pressed in the direction of the battery stack rather than the end plate and the pressing plate. Therefore, the pressing force is more easily applied to the first welded portion located on the outer peripheral edge side of the pressing plate, and unevenness of the surface pressure distribution is suppressed.

  Next, in one of the present invention, a pair of end plates (5) are provided on both sides of the battery stack (4), and each end plate (5) has leg portions (51, 52) at both ends. And bolts (11, 12) respectively attached to the leg portions (51, 52).

  Then, the battery stack (4) is placed between the pair of end plates (5), and the opposing end plates (5) come close to each other by tightening the bolts (11, 12), and the pressing plate (2) Is pressed against the battery stack (4).

  According to the present invention, when the restraint load is managed so as to have an appropriate size, the leg portions are provided at both ends of the end plate, and the leg portions of the opposite end plates are brought close to each other by tightening the bolts, and the pressing force is applied. It is easy to manage the restraint load.

  In addition, the code | symbol in parentheses as described in a claim and said each means thru | or description is an example which shows the correspondence with the specific means as described in embodiment mentioned later easily, and limits the content of invention is not.

It is a schematic block diagram which shows the half of the battery module which shows the principle in 1st Embodiment of this invention. It is a schematic block diagram which follows the arrow II-II line | wire of FIG. 1 in the said embodiment. It is a schematic block diagram which shows the half of the battery module at the time of a pressurizing force being generated to the press plate in the said embodiment. It is a schematic block diagram which follows the arrow IV-IV line | wire of FIG. 3 in the said embodiment. It is the graph showing the relationship between the restraint load in the said embodiment, and the internal resistance inside a flat type battery. It is a battery module perspective view in the said embodiment. It is a schematic block diagram which shows the internal structure of the battery module seen from the arrow VII direction of FIG. 6 in the said embodiment. It is the front view of the press plate seen from the arrow VIII direction of FIG. 7 in the said embodiment. It is the front view which looked at the deformation | transformation plate in the said embodiment from the arrow IX direction of FIG. FIG. 8 is a schematic configuration diagram showing a state in which a pressing force is applied in the internal configuration of the battery module of FIG. 7 in the embodiment. It is the schematic block diagram which showed the position of the 1st welding part and the 2nd welding part in the structure of FIG. 7 in the said embodiment. It is the perspective view which illustrated the battery pack which installed multiple battery modules in the said embodiment. It is a perspective view which shows the external shape of the battery pack with which the battery pack case in the said embodiment was covered. It is a front view of the deformation | transformation plate which consists of 4 square-shaped plate 1 set used for the battery module which shows 2nd Embodiment of this invention. It is a front view of a set of two X-shaped deformation plates used in a battery module showing a third embodiment of the present invention. It is a front view of a set of two H-shaped deformation plates used in a battery module showing a fourth embodiment of the present invention. It is a front view of a set of two Y-shaped deformation plates used in a battery module showing a fifth embodiment of the present invention. It is a front view of a set of two O-shaped deformation plates used in a battery module showing a sixth embodiment of the present invention. It is a table | surface which shows the example of the shape of a deformation | transformation plate, the number of welding points, and a position explaining other embodiment.

  A plurality of modes for carrying out the present invention will be described below with reference to the drawings. In each embodiment, parts corresponding to the matters described in the preceding embodiment may be denoted by the same reference numerals, and redundant description may be omitted. In the case where a part of the configuration is described in each form, the other forms described above can be applied to the other parts of the configuration.

  Not only combinations of parts that clearly indicate that the combination is possible in each embodiment, but also the embodiments are partially combined even if they are not clearly specified unless there is a problem with the combination. It is also possible.

(First embodiment)
The first embodiment of the present invention will be described below. First, the principle of the first embodiment of the present invention will be described with reference to FIGS. 1 to 5, and then the specific structure of the first embodiment will be described. FIG. 1 shows a half of a battery module 1 illustrating the principle of the first embodiment of the present invention. FIG. 2 shows a cross section taken along the line II-II in FIG.

  FIG. 3 shows the principle of the first embodiment when a pressing force is generated on the pressing plate 2 and shows a half of the battery module 1. FIG. 4 shows a cross section taken along the line IV-IV in FIG. 1 to 4 are cross-sectional views, but the cross-sectional hatching is omitted and is schematically illustrated.

  A battery stack 4 is formed by laminating a plurality of flat batteries 3 formed by sealing a power generation element inside a sheet-shaped outer package in the thickness direction of the flat batteries 3. A plurality of the battery stacks 4 are provided in the battery module 1. The battery stack 4 needs to be appropriately pressurized. When the flat battery 3 is swollen, the battery stack 4 can absorb stress due to the swollenness.

  For this purpose, a pair of battery stacks 4 shown in FIG. 1 is prepared, and both ends of a pair of outer end plates 5 are fastened with bolts (not shown) as indicated by arrows Y11 and Y12 (FIG. 3) and stacked. The flat battery 3 is pressed to restrain the expansion of the flat battery 3.

  In this case, the central part of the flat battery 3 is pressed when the flat battery 3 is expanded, but it is necessary to prevent the problem that the end of the flat battery 3 is not sufficiently pressed. In this case, the end plate 5 needs to be thick so as not to be extremely deformed, but it is necessary to prevent the weight from becoming excessive.

  In order to satisfy such a requirement, the restraint structure that restrains the battery stack 4 by pressing in the thickness direction has the following configuration. This constraining structure has a pressing plate 2 that presses the battery stack 4 in the thickness direction adjacent to the battery stack 4. The pressing plate 2 has a deformed plate 6 welded by first welding portions W11 and W12. Furthermore, the constraining structure has an end plate 5 welded to the deformation plate 6 by the second welded portions W21 and W22. The end plate 5 deforms the deformation plate 6 to apply a pressing force to the battery stack 4 via the pressing plate 2 and the stress relaxation material 7 made of a resin material.

  The first welds W11 and W12 are located closer to the outer peripheral edge of the pressing plate 2 than the second welds W21 and W22. Thereby, when the outer periphery of the end plate 5 is pressed in the thickness direction as indicated by arrows Y11 and Y12 in FIG. 3, the second welded portions W21 and W22, the deformed plate 6, and the first welded portions W11 and W12 are interposed. The pressing plate 2 is pressed in the direction of the battery stack 4. When this pressing is performed, a gap G <b> 1 (FIG. 3) is formed between the pressing plate 2 and the portion of the deformation plate 6 adjacent to the second welds W <b> 21 and W <b> 22.

  This will be described in more detail. The battery pack composed of the assembly of the battery modules 1 according to the first embodiment can be applied to various electric devices equipped with a single battery composed of a plurality of flat batteries 3. Various electric devices are a device, a computer, a vehicle, etc. which have a storage battery. The battery pack according to the first embodiment is used for a power source for traveling such as a hybrid vehicle using a combination of an internal combustion engine and a battery drive motor as a travel drive source, and an electric vehicle using a motor as a travel drive source.

  The flat battery 3 constituting the single battery is, for example, a nickel hydrogen secondary battery, a lithium ion secondary battery, or an organic radical battery. The battery pack can be installed in a space under a car seat, a space between a rear seat and a trunk room, a space between a driver seat and a passenger seat, and the like while being housed in a housing.

  The flat battery 3 has a thin flat plate-like outer case, and the outer case is formed of a laminate sheet. The laminate sheet is made of a highly insulating material. The flat battery 3 has an internal space that is sealed by sealing the ends of the laminated sheet folded in two, for example, by heat-sealing the ends. In this internal space, an electrode laminate, an electrolyte, a terminal connection part, a part of the positive terminal part, and a part of the negative terminal part are built.

  The remaining portions of the positive electrode terminal portion and the negative electrode terminal portion protrude from the outer case of the flat battery 3 to the outside. The terminals exposed from the outer case, and the terminals of different polarities in adjacent flat batteries 3 are electrically connected by a conductive member such as a bus bar.

  The connection between the bus bar and the electrode terminal portion is performed by, for example, screw tightening or ultrasonic welding. Therefore, the module total terminal portions installed at both ends of each battery module 1 electrically connected by a bus bar or the like are used for supplying electric power or discharging toward other electric devices.

  In the state of FIG. 1 in which no pressing force is applied, no large gap is generated between the end plate 5 and the deformation plate 6. A gap corresponding to the thickness of the deformation plate 6 is generated between the end plate 5 and the pressing plate 2.

  As shown in FIG. 3, the leg portions 51 and 52 at both ends of the end plate 5 are brought close to each other by tightening bolts (not shown) to generate a pressing force. When this pressing force is generated, a gap G1 is formed between the deformation plate 6 and the pressing plate 2 in the vicinity of the second welded portions W21 and W22 which are the inner welding locations. The gap G1 is also referred to as an inner gap. On the other hand, an outer gap is formed between the end plate 5 and the deformed plate 6 in the first welded portions W11 and W12 that are the outer welding locations.

  Thereby, the whole surface to be restrained of the flat battery 3 constituting the battery stack 4 can be pressed, and unevenness of the surface pressure distribution at the time of pressing can be suppressed. Therefore, when the flat battery 3 is swollen, the stress due to the swollenness can be absorbed better. Since the unevenness of the surface pressure distribution can be suppressed, it is possible to suppress the generation of gas inside each flat battery 3 during charging and discharging, and the deterioration of the battery performance due to the retention of this gas between the electrode plates of the power generation element. Can be suppressed. Furthermore, the weight of the end plate 5 can be reduced.

  The flat battery 3 includes a plurality of power generation elements connected in parallel. Each of the power generation elements has a power generation element electrode, and the connection distance between the power generation element electrodes changes due to uneven surface pressure distribution. Therefore, the resistance of the current paths connected in parallel varies depending on the connection distance, and local current concentration occurs. In the first embodiment, since unevenness of the surface pressure distribution can be suppressed, the occurrence of local current concentration can be suppressed, and battery efficiency can be improved and local heat generation can be suppressed.

  FIG. 5 is a graph showing the relationship between the restraining load and the internal resistance inside the flat battery. The restraining load must not be too large or too small. If the restraining load is too small, the internal resistance of the battery module increases due to local current concentration. When the restraint load is increased from this state, the internal resistance rapidly decreases and gradually increases again. Therefore, the pressing force is managed so that the restraining load becomes an appropriate size.

  More specifically, in FIG. 5, in the low load region R <b> 1, the resistance value is large because the distance between the electrodes inside the flat battery 3 is long. And since the gas generated inside the flat battery 3 accumulates between the electrodes, a portion that does not contribute to the reaction is generated. On the other hand, in the high load region (over-restraint region) R2, since the electrolyte exudes from between the electrodes and the amount of Li ions decreases, the resistance value of the internal resistance increases.

  Compared to these, in the appropriate load region R3, the distance between the electrodes is appropriate. Moreover, there is no shortage of Li ions due to leakage of the electrolyte. Furthermore, there is no occurrence of a portion based on the generated gas that does not contribute to the reaction. Thereby, the resistance value is minimized. If the surface pressure distribution is uneven, the above phenomenon may occur locally. Ideally, pressing the entire constraining surface uniformly with an appropriate load provides battery performance. Above it is necessary.

  Next, a specific configuration of the battery module of the present invention will be described with reference to FIGS. FIG. 6 shows a first embodiment of the battery module 1 of the present invention. The pair of outer end plates 5 have L-shaped legs 51 and 52 at the left and right ends, respectively.

  By fastening the legs 51 and 52 of the pair of opposite end plates 5 with the bolts 11 and 12, the flat battery 3 stacked between the pair of opposite end plates 5 is pressed, and the flat battery 3 is restrained.

  The end plate 5 is also called a module case, and is sandwiched between a pair of end plates 5 so that the battery stack 4 including the plurality of flat batteries 3 receives a pressing force from the end plate 5. The battery stack 4 is composed of a plurality of stacked flat batteries 3 formed by sealing a power generation element inside a sheet-shaped outer package. A cover 14 is placed on the upper surface of a module case 13 formed by connecting two end plates 5 with bolts 11 and 12, and a thermistor 15 is exposed to the outside through an opening 16 provided in the cover 14.

  On the right side of the module case 13, a module total minus terminal 17 that is a minus terminal of the battery stack 4 in which a plurality of flat batteries 3 are connected in series is provided. Further, on the side of the module total minus terminal 17, a module total plus terminal 18 that is a plus terminal of the battery stack 4 is provided.

  FIG. 7 shows the internal configuration of the battery module as seen from the direction of arrow VII in FIG. 6, and schematically shows a state where no pressing force acts between the two end plates 5. Between the two opposing end plates 5, a plurality of flat batteries 3 each having a power generation element sealed inside a sheet-like exterior body are installed. Between the flat batteries 3, a plurality of heat conduction plates 8 constituting a metal heat radiating plate are held.

  A flat battery 3 is formed by stacking a plurality of flat batteries 3 in the thickness direction of the flat battery 3. The battery stack 4 forms a battery series body, and is provided with a module total negative electrode portion 17d and a module total positive electrode portion 18d which are negative terminals. The module total minus electrode portion 17d and the module total plus electrode portion 18d are respectively connected to the module total minus terminal 17 and the module total plus terminal 18 shown in FIG. 6 and exposed to the outer surface of the battery module 1.

  In the battery module 1, an assembly in which a predetermined number of flat batteries 3 and heat conducting plates 8 are alternately stacked is sandwiched between restraining members via stress relieving materials 7 serving as buffer members from both ends in the stacking direction. It is a united body by applying the heading restraining force.

  The heat conduction plate 8 is a member that is in close contact with the outer case of the unit cell made of the flat battery 3 and helps the heat conductivity of the laminate sheet having a low heat conductivity, and has a high heat conductivity. The heat conduction plate 8 is made of, for example, aluminum, copper, or an alloy thereof. Moreover, the stress relaxation material 7 is comprised with a flexible rubber | gum or resin.

  In FIG. 7, the restraining structure is welded to the pair of pressing plates 2 that press the battery stack 4 in the thickness direction adjacent to the battery stack 4, and to the press plates 2 at a first welding portion described later. A total of four deformation plates 6. Moreover, the restraint structure has a pair of end plates 5 welded to the deformation plate 6 by the second welded portion. The end plate 5 deforms the deformation plate 6 and presses the pressing plate 2 against the battery stack 4.

  As shown in FIG. 6, the pair of end plates 5 are fastened with bolts 11 and 12 to constitute a front surface and a back surface of the module case 13. Left and right side insulating plates 21 and 22 are installed on the left and right side portions of the module case 13, and the battery stack 4 is held inside the module case 13.

  FIG. 8 shows the pressing plate 2 viewed from the direction of arrow VIII in FIG. As shown in FIG. 3, eight holes 23 for welding punched out by a press for welding the end plate 5 and the deformation plate 6 are provided in the central portion of the metal pressing plate 2.

  FIG. 9 shows a pair of left and right of the four deformed plates 6 on the lower side in FIG. 7 as viewed from the direction of the arrow IX in FIG.

  In FIG. 7, a set of deformation plates 6 shown in FIG. 9 is provided on each of the front side (lower side in FIG. 7) and the rear side (upper side in FIG. 7). Accordingly, two sets of deformation plates 6 as shown in FIG. 9 are provided in one battery module 1, and four deformation plates 6 are required.

  FIG. 10 shows an internal configuration of the battery module of FIG. 7 and schematically shows a state in which a pressing force acts between the two end plates 5. That is, in FIG. 10, the leg portions 51 and 52 (FIG. 6) at both ends of the pair of opposing end plates 5 are connected by the bolts 11 and 12.

  Then, by screwing the bolts 11 and 12, the pair of opposing end plates 5 applies a pressing force to the battery stack 4 through the deformation plate 6 as indicated by arrows Y101 to Y104 in FIG. 10. At this time, a gap G1 is formed.

  FIG. 11 virtually shows the positions of the first welds W11 and W12 and the second welds W21 and W22 with circles in the configuration of FIG. The end plate 5 and the deformation plate 6 are joined by the second welded portions W21 and W22. Furthermore, the deformation plate 6 and the pressing plate 2 are joined by the first welded portions W11 and W12.

  And 1st welding part W11, W12 is located in the outer periphery side of the press plate 2 rather than 2nd welding part W21, W22. Further, the deformation plate 6 is easier to deform than the end plate 5 and the pressing plate 2. That is, it is configured by selecting a material that easily deforms (a material having low rigidity) or a thin dimension that easily deforms.

  Thus, the end plate 5 and the deformation plate 6 are not joined together but are joined locally at the second welds W21 and W22. Furthermore, the deformation plate 6 and the pressing plate 2 are not joined together but are joined together locally at the first welds W11 and W12.

  Then, the end plate 5 does not directly press the pressing plate 2, but more uniformly by pressing through the deforming plate 6 which is deformed so that the gap G1 is formed at the center as shown in FIG. A pressing force is applied to the battery stack 4. When there is no deformation plate 6 and the end plate 5 directly presses the pressing plate 2, the pressing force indicated by the arrows Y101 to Y104 moves further to the left and right ends of the end plate 5. That is, the space between the arrows Y101 and Y102 and the space between the arrows Y101 and Y102 are widened, and the pressing force is concentrated on the outside, so that the uniform pressing force is not applied to the battery stack 4.

  A plurality of battery modules 1 are stacked to form a battery pack. FIG. 12 illustrates an example of a battery pack 30 using a plurality of the battery modules 1 of the first embodiment. A pack total plus terminal 31 and a pack total minus terminal 32 are provided at both left and right ends of the battery pack 30.

  From the pack total plus terminal 31 and the pack total minus terminal 32, the electrical output of the battery pack 30 is taken out. The battery pack 30 is fixed to a metal pedestal 33, and a cooler 34 is provided on the lower surface of the battery pack 30. The battery pack 30 is cooled by the heat exchange medium flowing in the cooler 34. The cooler 34 comprises a heat exchanger. A wire harness 35 is provided between the battery modules 1, and a service plug 36 is provided at the right end of the battery pack 30.

  FIG. 13 shows the outer shape of the battery pack 30 covered with the battery pack case 40. A battery control device 41 (also referred to as a battery ECU) is provided at the upper right end of the battery pack 30. A part of the smoke exhaust duct 42 protrudes from the battery pack case 40.

  Hereinafter, the battery pack 30 of FIGS. 12 and 13 will be specifically described. The battery pack 30 includes eight battery modules 1 in this example. The battery module 1 is composed of an assembly of flat batteries 3 that are a plurality of unit cells.

  The battery pack case 40 of FIG. 13 is a housing that forms a battery housing space in which the battery module 1 is housed. In the battery pack case 40, eight battery modules 1 are accommodated in a line.

  The battery control device 41 constitutes a battery monitoring unit that monitors the state of the battery pack 30. The battery control device 41 is connected to the flat battery 3 via a plurality of detection lines extending from detection terminals installed at predetermined positions of the flat battery 3 in order to detect information on the state of the flat battery 3. ing. The detection line is a communication line for transmitting information such as battery voltage or temperature to the battery monitoring device, for example. The detection terminals are a voltage measuring element, a temperature sensor, and other various sensors that detect information related to the state of the battery.

  The battery pack case 40 is provided with a seal member such as packing (not shown), and is sealed so that air in the battery housing space does not leak outside. When the internal pressure of the flat battery 3 becomes an abnormal pressure, the outer case of the flat battery 3 may break and internal gas may be released to the outside. When the gas is thus released, the battery housing space is filled with the gas, but the battery pack 30 includes a smoke exhaust duct 42 for discharging the gas to the outside. The smoke exhaust duct 42 allows the battery housing space in the battery pack case 40 to communicate with the outside of the battery pack.

  The service plug 36 is a current control device that connects the battery modules 1 and is a wiping type plug that can make the battery modules 1 non-conductive and conductive. The service plug 36 is installed on a plug base. For example, the service plug 36 is a non-energized switch that is operated at the time of maintenance. The service plug 36 can aim at a state where no current flows if the plug is removed, and the circuit of the battery pack 30 can be forcibly disconnected. .

(Operational effects of the first embodiment)
In the first embodiment, the battery module is formed by stacking a plurality of flat batteries 3 each having a power generation element sealed inside a sheet-shaped outer package in the thickness direction of the flat batteries 3. 4 is configured. Moreover, the battery module is provided with the restraint structure which presses and restrains the battery laminated body 4 in the thickness direction. And the said restraint structure is equipped with the press plate 2 which presses the battery laminated body 4 in the thickness direction, the deformation | transformation plate 6 welded to the press plate 2 by 1st welding part W11, W12, and the end plate 5. Yes.

  The end plate 5 is welded to the deformation plate 6 at the second welded portions W21 and W22, and deforms the deformation plate 6 to press the pressing plate 2 against the battery stack 4. Moreover, the press plate 2 is provided between the deformation | transformation plate 6 and the battery laminated body 4, and the 1st welding parts W11 and W12 are located in the outer peripheral edge side of the press plate 2 rather than the 2nd welding parts W21 and W22. .

  According to this, the whole surface to be restrained of the flat battery constituting the battery stack can be pressed, and unevenness of the surface pressure distribution at the time of pressing can be suppressed. Therefore, when the flat battery is swollen, the stress due to the swollenness can be absorbed better. Since unevenness of the surface pressure distribution can be suppressed, generation of gas in each flat battery during charging / discharging can be suppressed, and deterioration in battery performance due to the gas staying between the electrode plates of the power generation element can be suppressed. Furthermore, since it is not necessary to increase the rigidity of the end plate 5 more than necessary, the weight of the end plate 5 can be reduced.

  Next, when the outer peripheral edge side of the end plate 5 is pressed in the thickness direction, a gap G1 is formed between the pressing plate 2 and the portion of the deformed plate 6 adjacent to the second welded portions W21 and W22.

  According to this, since the gap G1 is formed, more pressing force is applied to the first welded portions W11 and W12 located on the outer peripheral side of the pressing plate 2 than the second welded portions W21 and W22. Unevenness of the surface pressure distribution is suppressed.

  Next, the deformation plate 6 is made of a material that is more easily deformed than the end plate 5 and the pressing plate 2 or a dimension that is easier to deform.

  According to this, a deformation | transformation plate deform | transforms easily, when it presses in a battery laminated body direction rather than an end plate and a press plate. Therefore, the pressing force is more easily applied to the first welded portion located on the outer peripheral edge side of the pressing plate, and unevenness of the surface pressure distribution is suppressed.

  Next, a pair of end plates 5 are provided on both sides of the battery stack 4, and each end plate 5 has leg portions 51, 52 at both ends and bolts 11, 12 attached to the leg portions 51, 52, respectively. Have Then, the battery stack 4 is placed between the pair of end plates 5, the opposing end plates 5 approach each other by tightening the bolts 11 and 12, and the pressing plate 2 is pressed against the battery stack 4.

  According to this, when managing the restraint load so as to have an appropriate size, the leg portions are provided at both ends of the end plate, and the leg portions of the opposite end plates are brought close to each other by tightening the bolts to thereby apply the pressing force. Since it is generated, the restraint load can be easily managed.

  As described above, the entire surface to be restrained of the flat battery 3 constituting the battery stack 4 can be pressed, and unevenness of the surface pressure distribution during pressing can be suppressed. Therefore, when the flat battery 3 is swollen, the stress due to the swollenness can be absorbed better. Since unevenness of the surface pressure distribution can be suppressed, generation of gas inside each flat battery 3 during charging and discharging can be suppressed, and deterioration in battery performance due to this gas remaining between the electrode plates of the power generation element can be suppressed. . Furthermore, the weight of the end plate 5 can be reduced.

  Next, there are a plurality of power generation elements connected in parallel inside the flat battery 3. Each power generation element has a power generation element electrode, and the connection distance between the power generation element electrodes changes due to uneven surface pressure distribution. Therefore, the resistance of the current paths connected in parallel varies depending on the connection distance, and local current concentration tends to occur. However, in the first embodiment, since unevenness of the surface pressure distribution can be suppressed, local current concentration can be prevented, and battery efficiency can be improved and local heat generation can be prevented.

  In the state where no pressing force is applied, a gap is not substantially generated between the end plate 5 and the deformation plate 6. In addition, a gap corresponding to the thickness of the deformation plate 6 is generated between the end plate 5 and the pressing plate 2 (FIG. 1).

  The pair of end plates 5 have leg portions 51 and 52 at both ends, respectively, the battery stack 4 is installed between the pair of end plates 5, and the opposite end plates 5 are in the leg portions 51 and 52. When the bolts 11 and 12 are tightened, they approach each other to generate a pressing force.

  When this pressing force is generated, a gap G1 is formed between the deformation plate 6 and the pressing plate 2 in the vicinity of the second welded portions W21 and W22 which are the inner welding locations. On the other hand, a gap is formed between the end plate 5 and the deformed plate 6 in the first welded portions W and W12 that are the outer weld locations.

  Thereby, when deformation | transformation arises in the end plate 5 (when bending | deflection generate | occur | produces), it becomes possible to press the whole restraint surface of the flat battery 3 uniformly. Further, the end plate 5 can be reduced in weight. This is possible because the welding point of the deformed plate 6 is separated into the center side and the peripheral side of the battery stack 4 and the deflection of the end plate 5 serving as the battery module case is not directly transmitted to the pressing plate 2. As described above, the restraining member includes the end plate 5, the deformation plate 6, and the pressing plate 2 that constitute the battery module case.

  The deformation plate 6 is formed of a material that is thinner than the end plate 5 and the pressing plate 2 and has a low strength. That is, since the deformation plate 6 is desired to be deformed before the end plate 5 or the like, it is made of a material that is weak in strength. Thereby, even if the end plate 5 is deformed, unevenness of the surface pressure distribution can be suppressed.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the following embodiments, the same components as those in the first embodiment described above are denoted by the same reference numerals, description thereof is omitted, and different configurations will be described. In addition, about 2nd Embodiment or less, the same code | symbol as 1st Embodiment shows the same structure, Comprising: The description which precedes is used.

  In the first embodiment, the deformation plate 6 uses a set of two rectangular plates on one side of the battery module 1 as shown in FIG. 9, but can be further divided. FIG. 14 shows a deformed plate 6 composed of a set of four quadrangular plates used in the battery module 1 showing the second embodiment of the present invention. Thus, when the number of deformation plates 6 is increased, the number of welding points also increases.

(Third embodiment)
Next, a third embodiment of the present invention will be described. A different part from above-described embodiment is demonstrated. FIG. 15 shows a set of two deformed plates 6 used in the battery module 1 according to the third embodiment of the present invention. The deformation plate 6 is an X-shaped plate.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described. A different part from above-described embodiment is demonstrated. FIG. 16 shows a set of two deformed plates 6 used in the battery module 1 according to the fourth embodiment of the present invention. The deformation plate 6 is an H-shaped plate.

(Fifth embodiment)
Next, a fourth embodiment of the present invention will be described. A different part from above-described embodiment is demonstrated. FIG. 17 shows a set of two deformed plates 6 used in the battery module 1 according to the fifth embodiment of the present invention. The deformation plate 6 is a Y-shaped plate that is symmetrical with respect to the left-right line.

(Sixth embodiment)
Next, a sixth embodiment of the present invention will be described. A different part from above-described embodiment is demonstrated. FIG. 18 shows a set of two deformed plates 6 used in the battery module 1 according to the sixth embodiment of the present invention. The deformation plate 6 is an O-shaped plate.

(Other embodiments)
In the above embodiment, the preferred embodiment of the present invention has been described. However, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the present invention. It is. The structure of the said embodiment is an illustration to the last, Comprising: The scope of the present invention is not limited to the range of these description. The scope of the present invention is indicated by the description of the scope of claims, and further includes meanings equivalent to the description of the scope of claims and all modifications within the scope.

  The welding point in the said 1st Embodiment consists of 1st welding part W11, W12 and 2nd welding part W21, W22. The number of welding points is 16 in total, as can be seen from the eight welding holes 23 for welding the end plate 5 and the deformation plate 6 at the center of the pressing plate 2 in FIG. However, the number of welding points may be 12 or 20.

  Further, the number and position of the welding points can be changed according to the shape of the deformation plate 6. FIG. 19 is a table showing an example of the shape of the deformation plate 6 and the number and position of welding points, and shows the planar shape of the battery module and the number and position of the welding points of the deformation plate in each shape.

  Next, in the above-described embodiment, the end plate sandwiches the battery stack, and the leg portions of the end plate are screwed together to restrain the battery stack. However, the end portion of the end plate may be directly screwed with a bolt instead of partially providing the leg portion. Further, not only screw tightening but also a caulking structure or a fastening structure using rivets may be used. Moreover, although the three types of members of the end plate, the deformation plate, and the pressing plate are assumed to be metal, they may all be made of resin.

  In the above-described embodiment, the single battery constituting each battery module can be formed of a square single battery. This rectangular unit cell is a flat rectangular parallelepiped whose outer peripheral surface is covered with an outer case made of, for example, aluminum or an aluminum alloy. Each battery module may be configured integrally by sandwiching a battery stack in which a predetermined number of cells and insulating spacers are alternately stacked from both ends in the stacking direction with a restraining member.

  In the above embodiment, the number of battery modules is not limited to the disclosed form. For example, two or more battery modules may be arranged in a row. Moreover, although the battery pack demonstrated by the said embodiment is installed in the vehicle etc. with the attitude | position which has a thermal radiation part downward and a battery pack case upward, it is not limited to this form. For example, the installation posture of the battery pack may be a posture in which the heat dissipating part is positioned upward and the battery pack case is positioned in a downward direction, or the heat dissipating part and the battery pack case are aligned in the lateral direction.

  Next, the stress relaxation material can be omitted. Alternatively, the pressing plate and the stress relaxation material may be integrated using a composite material.

  Moreover, in the said embodiment, the battery laminated body was installed between a pair of end plates. However, one end plate may be provided for one battery stack, and the outer peripheral edge of the end plate may be pressed against a pedestal or the like as shown in FIG.

DESCRIPTION OF SYMBOLS 1 Battery module 2 Press plate 3 Flat battery 4 Battery laminated body 5 End plate 6 Deformation plate G1 Crevice W11, W12 1st welding part W21, W22 2nd welding part 30 Battery pack

Claims (4)

A battery stack (4) in which a plurality of flat batteries (3) formed by sealing a power generation element inside a sheet-shaped exterior body are stacked in the thickness direction of the flat batteries (3);
A battery module (1) comprising: a restraint structure for restraining the battery stack (4) by pressing in the thickness direction;
The restraint structure is
A pressing plate (2) for pressing the battery stack (4) in the thickness direction;
A deformation plate (6) welded to the pressing plate (2) by a first weld (W11, W12);
An end plate (2) welded to the deformation plate (6) by a second weld (W21, W22), deforms the deformation plate (6) and presses the pressing plate (2) against the battery stack (4). 5) and
The pressing plate (2) is provided between the deformation plate (6) and the battery stack (4),
The battery module, wherein the first welded portion (W11, W12) is located closer to the outer peripheral edge of the pressing plate (2) than the second welded portion (W21, W22).   When the outer peripheral edge side of the end plate (5) is pressed in the thickness direction, the portion of the deformed plate (6) adjacent to the second welded portion (W21, W22) and the pressing plate (2) The battery module according to claim 1, wherein a gap (G1) is formed therebetween.   3. The battery module according to claim 1, wherein the deformation plate (6) is more easily deformed than the end plate (5) and the pressing plate (2). A pair of the end plates (5) are provided on both sides of the battery stack (4),
Each of the end plates (5) has legs (51, 52) at both ends and bolts (11, 12) attached to the legs (51, 52), respectively.
The battery stack (4) is installed between a pair of end plates (5), and the opposing end plates (5) approach each other by tightening the bolts (11, 12). The battery module according to any one of claims 1 to 3, wherein (2) is pressed against the battery stack (4).

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