Secondary battery module

Abstract

To accurately detect expansion of a plurality of cells forming a module even when the expansion of the cells is at a minute stage when the cells expand in a module case.SOLUTION: A secondary battery module includes: a plurality of secondary battery cells having an outer container in which a power generation element is housed inside, and a terminal formed on the outer container; a case having an insulating property, and housing the plurality of secondary battery cells so that long sides of the secondary battery cells face each other; a bus bar electrically connecting two adjacent terminals of the plurality of secondary battery cells housed in the case; a monitoring device electrically connected to the secondary battery cell via the bus bar and measuring a temperature and a voltage of the secondary battery cell; and a detection device configured to detect a deformation of the secondary battery cell via a terminal surface of the outer container on which the terminals are formed, which is a detection surface.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to a secondary battery module.

Background Art

[0002] Conventionally, a secondary battery module (hereinafter referred to as a "module") in which a plurality of secondary battery cells (hereinafter referred to as "cells") are arranged side by side in a module case and electrically connected by a conductive member is known. The module is used as a power source for vehicles, electronic devices, and other industrial applications. The material of the outer container (cell can) of a prismatic cell is, for example, aluminum. In the module, the internal pressure of the cell increases under charge and discharge conditions, and a phenomenon occurs in which a plurality of cells bulge. Also, in the module, the cells are often arranged side by side in the short side direction of the cell. Then, the bulging of the cells occurs almost simultaneously in all the cells in the module and becomes a deformation that destroys the module case over time. Therefore, it is necessary to detect the bulging of each cell.

[0003] Conventionally, there are techniques in which an operator who inspects the module determines the bulging of the cell based on a change in a label wound around the cell, a technique in which a band is attached to each cell to have a function of suppressing bulging, or a technique in which the bulging of the cell is estimated from the amount of change in the load of a fan that circulates a refrigerant for cooling the cell in the module case.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in modules, since multiple cells are housed in a case, it is difficult to visually determine cell swelling through labels. Furthermore, attaching metal bands to individual cells to suppress swelling increases the manufacturing costs of both the cells and the module. In addition, when estimating cell swelling from the load changes of the fan that circulates the refrigerant that cools the cells, the areas where cell swelling can be detected are limited, there are many false positives, and cell swelling cannot be detected if the cells are not being cooled.

[0006] In modules, there is a challenge in detecting cell swelling from a minute stage, for example, when multiple cells swell almost simultaneously within the module case. [Means for solving the problem]

[0007] To solve the above problems, the secondary battery module of this embodiment comprises: an outer container housing a power generation element inside; a plurality of secondary battery cells having terminals formed on the outer container; a case having insulating properties that houses the plurality of secondary battery cells arranged so that the long sides of the secondary battery cells face each other; a busbar that electrically connects two adjacent terminals of the plurality of secondary battery cells housed in the case; a monitoring device that is electrically connected to the secondary battery cells via the busbar and measures the temperature and voltage of the secondary battery cells; and a detection device that uses the terminal surface on which the terminals are formed on the outer container as a detection surface and detects deformation of the secondary battery cells via the terminal surface. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is an exploded perspective view of the module of this embodiment. [Figure 2] Figure 2 is a perspective view illustrating the arrangement of the cell, busbar, and detection device in the module of this embodiment. [Figure 3] Figure 3 is a perspective view illustrating the arrangement of cells and monitoring devices in the module of this embodiment. [Figure 4]Figure 4 is a cross-sectional view showing the state of the cell before it expands inside the case, cut along the height direction of the cell. [Figure 5] Figure 5 is a cross-sectional view showing the cell in a swollen state inside the case, cut along the height direction of the cell. [Figure 6] Figure 6 is an explanatory diagram illustrating the differences in the amount of expansion of multiple cells in a module, viewed from the short side of the cell. [Modes for carrying out the invention]

[0009] Below, illustrative and schematic embodiments of a secondary battery module 1 (hereinafter referred to as Module 1) are disclosed with reference to Figures 1 to 3. Module 1 is also referred to as a battery pack. In the following explanation, we will use a Cartesian coordinate system with X, Y, and Z axes. The X-axis direction includes the +X and -X directions. The Y-axis direction includes the +Y and -Y directions. The Z-axis direction includes, for example, the upward direction (+Z) and the downward direction (-Z). In Figures 1 to 3, for example, the X-Y axis plane is the horizontal plane, and the Z-axis direction is the vertical direction.

[0010] The module 1 of this embodiment comprises a plurality of secondary battery cells 2 (hereinafter referred to as cell 2), a case 5 having insulating properties and housing the plurality of cells 2, a busbar 3 electrically connecting two adjacent terminals of the plurality of cells 2 housed in the case 5, a monitoring device 4 electrically connected to the cell 2 via the busbar 3 and measuring the temperature and voltage of the cell 2, and a detection device 6 that uses the terminal surface 203 of the outer casing 20 of the cell 2 as a detection surface and detects deformation of the cell 2 via the terminal surface 203.

[0011] For example, in module 1, at least one of a series connection structure in which multiple cells 2 are electrically connected in series, and a parallel connection structure in which multiple cells 2 are electrically connected in parallel is formed.

[0012] Cell 2 is, for example, a non-aqueous electrolyte secondary battery such as a lithium-ion battery, and comprises a flat or substantially rectangular parallelepiped outer container 20 made of aluminum or an aluminum alloy, and a power generation element 27 housed together with a non-aqueous electrolyte inside the outer container 20. That is, cell 2 is, for example, a prismatic can cell.

[0013] The outer container 20 comprises a bottomed rectangular cylindrical container body 200 and a lid 201 integrally attached to an opening (not shown) of the container body 200 by melting or the like. The upper surface of the lid 201 in the Z-axis direction is designated as the terminal surface 203. Two types of terminals, a positive terminal 23 and a negative terminal 24, are formed at intervals in the regions on both sides of the terminal surface 203 in the longitudinal direction (X-axis direction).

[0014] Furthermore, cell 2 is equipped with a labuture 25 in the center of the terminal surface 203 for discharging gas generated inside the outer container 20, and an injection port 26 for injecting non-aqueous electrolyte into the outer container 20. The labuture 25 is, for example, an X-shaped groove provided in the thin-walled portion located between the positive terminal 23 and the negative terminal 24 of the lid 201.

[0015] The outer container 20 has a bottom surface 204 facing the terminal surface 203 in the Z-axis direction, a pair of short sides 205 that are continuous with the bottom surface 204, and a pair of long sides 206 that are continuous with the bottom surface 204. In Figure 1, the pair of short sides 205 are opposing surfaces in the X-axis direction. The pair of long sides 206 are opposing surfaces in the Y-axis direction. In addition, the long sides 206 of the multiple cells 2 housed in the case 5 face each other in the Y-axis direction. Under normal circumstances, the terminal surface 203, bottom surface 204, pair of short sides 205, and pair of long sides 206 of the cell 2 are flat surfaces.

[0016] The positive terminal 23 and negative terminal 24 for current input and output are attached to the cover 201 by crimping them to the cover 201 or by being cast into the cover 201 during its molding process. The positive terminal 23 and negative terminal 24 are electrically insulated from the cover 201. The positive terminal 23 and negative terminal 24 are formed, for example, in a substantially flat plate shape.

[0017] The power generation element 27, which is housed inside the outer container 20 and is shown in a simplified manner by a broken line, has its positive electrode electrically connected to the positive electrode terminal 23. The negative electrode of the power generation element 27 is electrically connected to the negative electrode terminal 24. The power generation element 27 includes, for example, a wound electrode group.

[0018] The case 5 is formed of a material having electrical insulation properties. Examples of the material forming the case 5 include resins such as polyphenylene ether, polycarbonate, and polybutylene terephthalate. The case 5 houses, for example, nine cells 2. Inside the case 5, for one cell 2 and another cell 2 located adjacent to the one cell 2, the positions of the positive electrode terminal 23 and the negative electrode terminal 24 in the X-axis direction are opposite. Here, the plurality of cells 2 housed in the case 5 are taken as one cell row 2A.

[0019] The case 5 includes a box portion 51. The box portion 51 includes a pair of side walls 512 facing each other in the longitudinal direction (Y-axis direction) of the case 5, a pair of side walls 513 facing each other in the short side direction (X-axis direction) of the case 5, and a bottom plate 515. The pair of side walls 512, the pair of side walls 513, and the bottom plate 515 are integrally formed.

[0020] The box portion 51 includes a plurality of partition walls 516. Each partition wall 516 is disposed between the pair of side walls 512 in the Y-axis direction. The inside of the box portion 51 is partitioned into nine accommodation chambers 517 equal in number to the number of cells 2 in the Y-axis direction by, for example, eight partition walls 516 arranged at equal intervals and spaced apart from each other. The partition wall 516 is formed of a material having electrical insulation properties at least on its outer surface and also functions as a separator.

[0021] Each of the storage compartments 517 of the box section 51 houses one cell 2, with the long sides 206 of the cells 2 facing each other in the Y-axis direction. For example, adhesive is provided on the upper surface of the bottom plate 515 (the bottom surface of the storage compartment 517), and the bottom surface 204 of the cell 2 is bonded and fixed to the bottom plate 515 by the adhesive. In addition, the partition walls 516 ensure that the multiple cells 2 are properly positioned in the Y-axis direction. The adhesive, which is not shown, is, for example, a two-component epoxy resin adhesive, but is not limited to this, and may also be an ultra-thin double-sided tape.

[0022] In cell column 2A, the shorter side of each cell 2 is parallel or approximately parallel to the longer side (Y-axis direction) of Case 5, and the longer side of each cell 2 is parallel or approximately parallel to the shorter side (X-axis direction) of Case 5. Furthermore, in cell column 2A, the height direction of each cell 2 is parallel or approximately parallel to the height direction (Z-axis direction) of Case 5.

[0023] As shown in Figure 1, the case 5 is equipped with a resin cover 52 that serves as a top plate for the box portion 51. The resin cover 52 comprises a flat plate portion 520 formed in a rectangular shape in plan view, a lower frame portion (not shown) hanging down in the outer peripheral region of the lower surface of the flat plate portion 520, a wall portion 521 erected in the outer peripheral region of the upper surface of the flat plate portion 520, and a plurality of terminal exposure holes 523 that penetrate the flat plate portion 520 in the thickness direction (Z-axis direction).

[0024] The upper portion of the cell row 2A housed in the box portion 51 fits into the space enclosed by the lower surface of the flat plate portion 520 and a lower frame portion (not shown). In addition, the positive terminal 23 and negative terminal 24 of each cell 2 are exposed on the upper surface of the flat plate portion 520 through the terminal exposure holes 523 of the flat plate portion 520.

[0025] As shown in Figure 1, the upper surface of the resin cover 52 is surrounded on all four sides by a wall portion 521, and a housing portion 528 for housing the busbar 3 and the monitoring device 4 is formed therein.

[0026] The busbar 3 is, for example, formed from aluminum or an aluminum alloy in a rectangular flat plate shape, with brazing material placement holes 32 formed one by one in the thickness direction, aligned along the longitudinal direction (Y-axis direction). The brazing material placement holes 32 are counterbore holes for laser welding using brazing material, into which the molten brazing material is placed. Note that the shape of the busbar 3 is not limited to the example shown in Figure 1.

[0027] A busbar 3 is laser-welded using brazing material to the positive terminal 23 and negative terminal 24 of a cell 2 exposed through a terminal exposure hole 523 in the resin cover 52 shown in Figure 1. Specifically, as shown in Figure 2, one end of the busbar 3 in the Y-axis direction is welded to the positive terminal 23 of one cell 2, and the other end of the busbar 3 in the Y-axis direction is welded to the negative terminal 24 of an adjacent cell 2 in the Y-axis direction. In addition, the negative terminal 24 of one cell 2 is welded to the positive terminal 23 of an adjacent cell 2 on the opposite side from the aforementioned adjacent cell by the busbar 3. Figure 2 is a perspective view illustrating the arrangement of the cell 2, busbar 3, and detection device 6 in module 1 of this embodiment. In Figure 2, a case 5 containing multiple cells 2 is shown in a simplified form with a dashed line.

[0028] For example, among the multiple cells 2 housed in case 5 shown in Figure 2, the positive terminal 23 of a cell 2 located at the end position in the -Y direction within case 5 that is not connected by the busbar 3 is connected via the busbar to a positive power input / output terminal (not shown). For example, among the multiple cells 2 housed in case 5, the negative terminal 24 of a cell 2 located at the end position in the +Y direction within case 5 that is not connected by the busbar 3 is connected via the busbar to a negative power input / output terminal (not shown). The module 1 is charged and used by connecting the positive power input / output terminal (not shown) and the negative power input / output terminal (not shown) to a charging power supply or load.

[0029] In this way, multiple cells 2 are connected, for example, in series by multiple busbars 3 to form a module 1. In a module 1 that includes multiple cells 2 that are electrically connected in parallel, the multiple cells 2 can be electrically connected, for example, by connecting the negative terminals 24 together by busbars 3 and the positive terminals 23 together by busbars 3.

[0030] The monitoring device 4 shown in Figure 1 is, for example, a rectangular plate-shaped monitoring board, also known as a CMU (Cell Monitoring Unit) board. The monitoring device 4 is equipped with a cell monitoring IC, etc., measures the voltage and temperature of cell 2, and is configured to exchange data with a higher-level control device (not shown), for example. An example of a higher-level control device is a BMU (Battery Management Unit). The monitoring device 4 has the function of controlling each of the multiple cells 2 of module 1. The monitoring device 4 may also measure the charge and discharge amounts of cell 2, etc. For example, the resin cover 52 is equipped with an external communication connector (not shown), and the monitoring device 4 exchanges data with the higher-level control device through this external communication connector.

[0031] The monitoring device 4 is housed in the housing section 528 of the resin cover 52. Also, as shown in Figure 3, for example, the lower surface, which is the mounting surface 40, is connected to the upper surface of the multiple busbars 3 welded to the multiple cells 2. In Figure 3, the case 5 shown in Figure 1 is simplified with a dashed line to show the connection relationship between the monitoring device 4, the busbars 3 and the cells 2.

[0032] As shown in Figure 1, module 1 is equipped with a protective cover 19 to protect the monitoring device 4 electrically connected to the busbar 3 and cell 2. The protective cover 19 is formed in the shape of a rectangular plate with upper and lower flat surfaces from an electrically insulating material, and is placed in the housing portion 528 of the resin cover 52 so as to cover the monitoring device 4 from above.

[0033] As shown in Figure 1, a detection device 6 is mounted on the mounting surface 40 of the monitoring device 4 facing the cell 2, using the terminal surface 203 of the outer container 20 of the cell 2 as the detection surface, and detecting deformation of the cell 2 via the terminal surface 203. In other words, in this embodiment, the detection device 6 is integrated with the monitoring device 4.

[0034] The detection device 6 in this embodiment is, for example, a contact-type temperature sensor that contacts the terminal surface 203 of cell 2. The detection device 6, which is a contact-type temperature sensor, is, for example, a thermocouple that measures by connecting the ends of two different metal wires to the terminal surface 203 and utilizing the principle that a thermoelectric voltage is generated by the temperature difference between the end and the other end. The detection device 6, which is a contact-type temperature sensor, may also be a resistance thermometer that measures by utilizing the property that the electrical resistance of a metal increases or decreases in proportion to temperature, or a thermistor that measures by utilizing the property that the resistance value changes significantly with temperature changes in an element made by sintering a metal oxide.

[0035] The detection device 6 is positioned, for example, to extend from the mounting surface 40 of the monitoring device 4 toward the terminal surface 203 of the cell 2. As shown in Figure 1, the resin cover 52 has a through hole 527 formed through it to allow the detection device 6 to pass through in the thickness direction (Z-axis direction). The detection device 6, which is integrated with the monitoring device 4, is housed in the housing section 528 of the resin cover 52, as shown in Figure 3. Within the housing section 528, the detection device 6 passes through the through hole 527, as shown in Figure 4, and contacts the terminal surface 203 of the cell 2. Figure 4 is a cross-sectional view showing a portion of the module 1, which is a combination of the case 5, cell 2, busbar 3, monitoring device 4, and protective cover 19 shown in Figure 1, cut along the height direction (Z-axis direction) and enlarged. In Figure 4, the power generation elements 27 etc. inside the outer container 20 are omitted. Also, Figure 4 shows the state of the cell 2 before it expands. The detection device 6 measures the temperature of cell 2 via the terminal surface 203 and sequentially transmits the measurement information to the monitoring device 4.

[0036] In this embodiment, the detection device 6 contacts the terminal surfaces 203 of two cells 2 located at both ends of the case 5 in the direction in which the cells 2 are arranged (Y-axis direction), out of the nine cells 2 housed in the case 5. The detection device 6 may also be configured in the monitoring device 4 to contact the terminal surface 203 of a cell 2 other than the two cells 2 located at both ends of the case 5 in the Y-axis direction, and to measure the temperature of that other cell 2.

[0037] In addition, in module 1, multiple detection devices 6 may be arranged on the mounting surface 40 of the monitoring device 4 such that at least one contact is made with each of the terminal surfaces 203 of the nine cells 2 housed in case 5. That is, for example, all of the multiple cells 2 in case 5 may have their temperature measured individually by their respective detection devices 6. Accordingly, multiple through holes 527 may be formed in the resin cover 52 shown in Figure 1, spaced apart in the Y-axis direction.

[0038] Module 1 of this embodiment is equipped with, for example, multiple (two) detection devices 6 corresponding to one cell 2. In Figure 1, two detection devices 6 correspond to one cell 2 located at the -Y end position in the direction in which the cells 2 are arranged in the case 5 (Y-axis direction), and two other detection devices 6 correspond to one cell 2 located at the +Y end position in the direction in which the cells 2 are arranged in the case 5 (Y-axis direction). The two detection devices 6 corresponding to one cell 2 are arranged on the mounting surface 40 of the monitoring device 4 at a predetermined interval in the X-axis direction.

[0039] Two detection devices 6 aligned in the X-axis direction pass through the through-hole 527 of the resin cover 52 and each contact the terminal surface 203 of a cell 2 located at the -Y-direction end position within the case 5. For example, one of the two detection devices 6 aligned in the X-axis direction contacts the area between the lubricant 25 and the positive terminal 23 on the terminal surface 203 of a cell 2. The other detection device 6 aligned in the X-axis direction contacts the area between the lubricant 25 and the negative terminal 24 on the terminal surface 203. In other words, in this embodiment, there are two detection devices 6 corresponding to each of the multiple cells 2 housed in the case 5, and the two detection devices 6 simultaneously detect the deformation of the cell 2 via the terminal surface 203. Similarly, two other detection devices 6, separate from the two detection devices 6 described above, also contact the terminal surface 203 of a cell 2 located at the +Y-direction end position within the case 5. Furthermore, one detection device 6 may correspond to (contact) a single cell 2, or three or more detection devices 6 may correspond to (contact) a single cell 2.

[0040] Module 1, shown in Figures 1 to 3, is charged when power is supplied to it from a power source (not shown). Module 1 is discharged when power is supplied from it to a load. The following describes the process by which the detection device 6 detects swelling of each cell 2 in Module 1 of this embodiment when each cell 2 swells due to repeated charging and discharging.

[0041] As shown in Figures 1 to 4, when cell 2 has not yet swollen due to repeated charging and discharging, the terminal surface 203, bottom surface 204, a pair of short sides 205, and a pair of long sides 206 of cell 2 are flat surfaces. In this embodiment, in this state, as shown in Figure 4, the detection device 6, which is composed of a contact-type temperature sensor, is in contact with the terminal surface 203 of cell 2.

[0042] As each cell 2 of module 1 shown in Figures 1 to 3 undergoes repeated charging and discharging, the cell 2 generates heat. Specifically, the heat generated by charging and discharging is approximated by the product of its internal resistance and the square of the charging / discharging current. Furthermore, since the power generation element 27 inside the cell 2 is housed with an electrolyte wound around a coil, its thermal conductivity differs depending on the winding direction, stacking direction, and in-plane direction, and the ease of heat dissipation differs for each face of the prismatic cell 2. In this heat generation, the center of the cell 2 generates the most heat, and the amount of heat generated decreases as you move from the center of the cell 2 towards the outer surface of the cell 2. Specifically, in the cell 2 shown in Figure 1, the pair of long sides 206, which have the largest surface area, generate the most heat, while the amount of heat generated decreases as you move towards the pair of short sides 205, the bottom surface 204, and the terminal surface 203 of the cell 2.

[0043] When the internal pressure of the prismatic cell 2 increases due to heat generation, the cell bulges from the state shown in Figure 4 to the state shown in Figure 5. That is, as shown in Figure 5, the pair of long sides 206 with a large surface area of ​​the outer container 20 bulge outward in the Y-axis direction. Note that in Figure 5, the power generation element 27 inside the outer container 20 is omitted from the illustration. On the other hand, the pair of short sides 205 (see Figure 1) deform inward in the X-axis direction (towards the center of cell 2), the bottom surface 204 deforms inward in the Z-axis direction (towards the center of cell 2), and the terminal surface 203 deforms inward in the Z-axis direction (towards the center of cell 2). This is because the pair of long sides 206, which have the largest surface area, bulge outward, causing the force moment generated by the bulging of the pair of long sides 206 to act on the pair of short sides 205, the bottom surface 204, and the terminal surface 203, with the boundary portions between the pair of long sides 206 and the pair of short sides 205, the boundary portions between the pair of long sides 206 and the bottom surface 204, and the boundary portions between the pair of long sides 206 and the terminal surface 203 acting as fulcrums.

[0044] As module 1 is charged and discharged, in the first stage a small swelling occurs in cell 2 as shown in Figure 5, in the second stage case 5 which houses multiple cells 2 as shown in Figures 1 to 3 swells, in the third stage multiple cells 2 burst out of case 5, and in the fourth stage the lubricator 25 of cell 2 is activated, causing the non-aqueous electrolyte and the like from the outer container 20 to be ejected from the lubricator 25.

[0045] As shown in Figures 1 and 2, in cell row 2A where cells 2 are arranged in a line, the coupling strength on the terminal surface 203 side of each cell 2 connected by the busbar 3 is greater due to the busbar 3 than the coupling strength at other parts of the cell 2. Therefore, as shown in Figure 6, in each cell 2, the terminal surface 203 side becomes the center of rotation, and the cells 2 push against each other as the long side 206 bulges, creating a larger gap between each cell 2 on the bottom surface 204 side. Note that in Figure 6, cases such as Case 5 are omitted in order to explain the differences in the degree of bulging of each cell 2.

[0046] In the case 5 shown in Figures 1 and 2, among the nine cells 2 housed in the case 5, the degree of bulging is greater for cells 2 located further out from the center than for cells 2 located in the center in the direction in which the cells 2 are arranged (Y-axis direction). That is, in the case of multiple cells 2 located towards the center in the Y-axis direction shown in Figure 6, adjacent cells 2 push against each other as their long sides 206 bulge, but cells 2 located further out are subjected to less force from adjacent cells 2.

[0047] As shown in Figure 6, among the multiple cells 2 housed in case 5 (see Figure 1), the long sides 206 of the two cells 2 located at both ends in the Y-axis direction bulge outward the most, while the pair of short sides 205, bottom surface 204, and terminal surface 203 of these two cells 2 located at both ends are recessed inward (towards the center of the cell 2).

[0048] In the first stage where cell 2 bulging occurs, the multiple cells 2 forming module 1 are housed and covered in case 5 as shown in Figures 1 and 5, so the minute bulging of cell 2 cannot be seen with the naked eye. Furthermore, the monitoring device 4 observes almost no change in voltage information obtained from the charge / discharge state of each cell 2.

[0049] In module 1 of this embodiment, of the nine cells 2 housed in case 5 shown in Figures 1 to 3, the terminal surfaces 203 of the two cells 2 located at both ends in the direction in which the cells 2 are aligned (Y-axis direction) and which have the largest bulging change, become concave, causing the contact between the detection device 6, which is a contact-type temperature sensor, and the terminal surfaces 203 to be lost, as shown in Figure 5. That is, the deformation of the cell 2 from the state shown in Figure 4 to the state shown in Figure 5 causes a change in the measurement value of the detection device 6, which was measuring the temperature of the cell 2. This change is, for example, a decrease in the measurement value of the temperature of the cell 2 of the detection device 6 because the terminal surface 203 is concave and physically separated from the detection device 6. In other words, even minute bulging of the cell 2 that could not be detected conventionally can now be detected by the detection device 6.

[0050] The detection device 6 may be formed not by a contact-type temperature sensor as in this embodiment, but by, for example, a pressure sensor. When the detection device 6 is a pressure sensor, as shown in Figure 4, the detection device 6 is in contact with the terminal surface 203 of the cell 2 before it bulges, and receives a predetermined contact pressure from the terminal surface 203. Then, as shown in Figure 5, when the terminal surface 203 of the cell 2 dents and the contact between the detection device 6 and the terminal surface 203 is lost, a change occurs in the measured value of the detection device 6, causing it to decrease. Because the terminal surface 203 physically separates from the dent detection device 6, even minute bulges in the cell 2 that could not be detected conventionally can now be detected by the detection device 6.

[0051] For example, the detection device 6, which is a temperature sensor, may not be in contact with the terminal surface 203 of cell 2 when the cell 2 is not bulging as shown in Figure 4, and may be at a predetermined distance from the terminal surface 203 in the Z-axis direction, while the detection device 6 is sequentially measuring the temperature of cell 2 via the terminal surface 203. As shown in Figure 5, the terminal surfaces 203 of the two cells 2 located at both ends in the direction in which the cells 2 are arranged in case 5 (Y-axis direction) become concave, increasing the distance between the detection device 6 and the terminal surface 203 in the Z-axis direction. As a result, the temperature measurement of cell 2 by the detection device 6 decreases because the terminal surface 203 is concave and physically moves further away from the detection device 6. In other words, even minute bulges in cell 2 that could not be detected conventionally can now be detected by the detection device 6. If the detection device 6 is a non-contact temperature sensor, for example, the temperature can be measured by capturing the thermal energy radiation emitted from the terminal surface 203. Furthermore, the detection device 6 is not limited to a non-contact temperature sensor. For example, the detection device 6 may be a capacitive sensor that forms a capacitor between itself and the terminal surface 203 of the cell 2, and detects the deformation of the cell 2 by measuring the displacement of the terminal surface 203 of the cell 2, i.e., by measuring the change in the capacitance of the capacitor.

[0052] In this embodiment, as shown in Figure 1, two detection devices 6 are arranged at a predetermined distance in the X-axis direction for each of the two cells 2 housed in the case 5 at both ends in the Y-axis direction. Each of the two detection devices 6 aligned in the X-axis direction detects the deformation of one of the cells 2 located at the -Y-direction end position when the above-mentioned change in the temperature measurement occurs.

[0053] From the two detection devices 6 installed on the mounting surface 40 of the monitoring device 4, detection information indicating that one cell 2 located at the end position in the -Y direction has been deformed is sent to the monitoring device 4. The monitoring device 4 then combines the detection information from the two detection devices 6, which are arranged side by side in the X-axis direction, and determines that there has been deformation (bulging) of one cell 2 located at the end position in the -Y direction. Specifically, the monitoring device 4 determines that bulging deformation of cell 2 has occurred when both detection devices 6 send detection information about bulging of cell 2. Alternatively, the monitoring device 4 may determine that deformation (bulging) has occurred in each cell 2 within case 5 when it receives detection information from either of the two detection devices 6 indicating that there has been deformation of one cell 2 located at the end position in the -Y direction, without combining the detection information from the two detection devices 6 arranged side by side in the X-axis direction.

[0054] Furthermore, the monitoring device 4 may receive detection information from each of the two detection devices 6 arranged side by side in the X-axis direction in the -Y-direction region of the installation surface 40 indicating that there has been deformation in one cell 2 located at the -Y-direction end position within the case 5, and also receive detection information from each of the two detection devices 6 arranged side by side in the X-axis direction in the +Y-direction region of the installation surface 40 indicating that there has been deformation in one cell 2 located at the Y-direction end position. The monitoring device 4 may then combine this detection information to determine that bulging has occurred in each cell 2 within the case 5.

[0055] Module 1 of this embodiment comprises an outer container 20 in which a power generation element 27 is housed, a plurality of cells 2 having positive terminals 23 and negative terminals 24 formed on the outer container 20, a case 5 having insulating properties that houses the plurality of cells 2 arranged so that the long sides 206 of the cells 2 face each other, a busbar 3 that electrically connects adjacent cells 2, for example, a positive terminal 23 and a negative terminal 24, among the plurality of cells 2 housed in the case 5, a monitoring device 4 that is electrically connected to the cells 2 via the busbar 3 and measures the temperature and voltage of the cells 2, and a detection device 6 that uses the terminal surface 203 on which the positive terminals 23 and negative terminals 24 are formed on the outer container 20 as a detection surface and detects deformation of the cells 2 via the terminal surface 203. In the sealed module 1, the terminal surface 203 on which the positive terminals 23 and negative terminals 24 are arranged in the plurality of cells 2 housed in the case 5 is a surface within the outer container 20 that can be directly or indirectly exposed to the outside of the case 5. Furthermore, compared to the pair of long sides 206, the pair of short sides 205, and the bottom surface 204 of the prismatic cell 2, which are difficult to expose within the case 5, the terminal surface 203 is a surface that is easier to detect deformations such as bulging and denting of the cell 2. Also, due to the structure of the module 1, the monitoring device 4, such as a CMU that measures the temperature and voltage of the cell 2, needs to be placed above the terminal surface 203, but the detection device 6 can be easily placed near the monitoring device 4. For example, in this embodiment, by using the lower surface of the monitoring device 4 facing the terminal surface 203 as the mounting surface 40, and placing the detection device 6 that detects deformation of the cell 2 via the terminal surface 203 on the mounting surface 40, it becomes possible for the detection device 6 to detect bulging of the cell 2 at a minute stage. In other words, it becomes possible to prevent the case 5, which houses multiple cells 2, from bulging due to the bulging of the cells 2.

[0056] For example, the detection device 6 is in contact with the terminal surface 203 of a cell 2 that has not yet swollen, and measures the temperature of the cell 2 via the terminal surface 203. It detects the deformation of the cell 2 when the terminal surface 203 dents and contact with the terminal surface 203 is lost. This makes it possible to detect minute dents in the terminal surface 203, or in other words, minute bulges in the cell 2, at an earlier stage.

[0057] For example, the detection device 6 detects deformation of a cell 2 located at the end position in the direction in which the cells 2 are arranged within the case 5 (Y-axis direction), among the multiple cells 2 housed in the case 5. In the case 5, multiple cells 2 located towards the center in the Y-axis direction are pushed against each other by the bulging of their long sides 206, and this bulging of the long sides 206 is suppressed by this pushing, and as a result, the indentation of the terminal surface 203 is also suppressed. In contrast, in the case 5, cells 2 located at the end position in the Y-axis direction are subjected to less force from the adjacent cells 2, resulting in a larger bulge of the long side 206 and a larger indentation of the terminal surface 203. Therefore, for example, the contact-type detection device 6 will disengage from the terminal surface 203 earlier than any other cell 2 housed in the case 5. In other words, when detecting the bulging of multiple cells 2 occurring almost simultaneously within the module 1, it becomes possible to detect minute bulges of cells 2 at an earlier stage, and false detections can be suppressed.

[0058] For example, since the detection device 6 is integrated with the monitoring device 4, information about the detection of bulging in the cell 2 inside the case 5 by the detection device 6 can be easily transmitted to the monitoring device 4. Also, due to the structure of the module 1, the monitoring device 4 needs to be positioned above the terminal surface 203, so integrating the detection device 6 with the monitoring device 4 is structurally suitable for the module 1 in order to make the terminal surface 203 the detection surface.

[0059] In module 1 of this embodiment, for example, multiple detection devices 6 are provided, and for each cell 2 located at both ends in the direction of arrangement of the cells 2 (Y-axis direction) among the multiple cells 2 housed in case 5, two detection devices 6 make contact and detect deformation via terminal surfaces 203. That is, for each cell 2 to be detected, two detection devices 6 simultaneously perform bulging detection. Then, detection information indicating that one cell 2 located at the end position on the -Y direction side has deformed is sent from the two detection devices 6 to the monitoring device 4. The monitoring device 4 determines that bulging has occurred in cell 2 if, for example, both of the two detection devices 6 arranged side by side in the X-axis direction send detection information about bulging in one cell 2. If only one of the two detection devices 6 arranged side by side in the X-axis direction sends detection information about bulging deformation in cell 2, the monitoring device 4 determines that bulging deformation has not yet occurred in cell 2. In this way, the monitoring device 4 integrates the detection information from multiple detection devices 6 to determine whether or not cell 2 is deformed, thereby reducing the frequency of false detections and improving detection accuracy compared to the case where only a single detection device 6 is used to detect bulging in a single cell 2. For example, if three or more detection devices 6 are installed in a single cell 2, the monitoring device 4 may determine that bulging deformation of cell 2 has occurred when, for example, detection information indicating that cell 2 has been deformed has been sent from more than half of the detection devices 6.

[0060] In addition, in the module 1 shown in Figure 1, multiple detection devices 6 may be arranged on the mounting surface 40 of the monitoring device 4 such that at least one detection device 6 contacts each terminal surface 203 of all the cells 2 housed in the case 5. Furthermore, for example, all of the multiple cells 2 in the case 5 may have their temperature measured individually by their respective detection devices 6, thereby detecting whether or not swelling is occurring sequentially.

[0061] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0062] 1: Module, 19: Protective cover 2: Cell, 2A: Cell column 20: Outer container, 203: Terminal surface, 204: Bottom surface, 205: Short side 206: Long side 23: Positive terminal, 24: Negative terminal, 25: Lavender, 27: Power generation element 3: Bus bar 4: Monitoring device, 40: Connection surface 5: Case 51: Box section, 516: Partition wall, 517: Containment chamber 52: Resin cover, 523: Terminal exposure hole, 527: Through hole 6: Detection device

Claims

1. A secondary battery cell comprising an outer casing containing a power generation element, and a plurality of secondary battery cells having terminals formed on the outer casing, A case having insulating properties, which houses multiple secondary battery cells arranged so that their long sides face each other, A busbar that electrically connects two adjacent terminals of the multiple secondary battery cells housed in the case, A monitoring device electrically connected to the secondary battery cell via the busbar, which contacts the terminals of the secondary battery cell to measure the temperature and voltage of the secondary battery cell, A detection device that uses the terminal surface on which the terminals are formed on the outer container as a detection surface, and detects deformation of the secondary battery cell by measuring the temperature of the secondary battery cell through the terminal surface and observing the change in the measured value, A secondary battery module equipped with the following features.

2. The detection device contacts the terminal surface and measures the temperature of the secondary battery cell through the terminal surface, and detects deformation of the secondary battery cell by the change in the measured temperature of the secondary battery cell that occurs when the contact with the terminal surface is lost. The secondary battery module according to claim 1.

3. The detection device detects deformation of a secondary battery cell located at the end position in the direction in which the secondary battery cells are arranged within the case, among the plurality of secondary battery cells housed in the case. A secondary battery module according to claim 1 or 2.

4. The secondary battery module according to claim 1 or 2, wherein the detection device is integrated with the monitoring device.

5. The device comprises multiple of the aforementioned detection devices, With respect to one of the multiple secondary battery cells housed in the case, the multiple detection devices detect deformation through the terminal surface, The monitoring device comprehensively analyzes the detection information from each of the multiple detection devices and determines whether or not the secondary battery cell is deformed based on the presence or absence of deformation of the secondary battery cell where at least two pieces of detection information match. The secondary battery module according to claim 4.

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