JP7236653B2 - battery unit - Google Patents

Description

TECHNICAL FIELD The present disclosure relates to battery units , and more particularly to battery units that house a plurality of battery cells.

A battery cell such as a lithium-ion secondary battery includes an insulating layer between a positive electrode plate and a negative electrode plate, which electrically insulates the respective electrode plates and serves to retain an electrolyte. Conductor powder (foreign matter) adhering to the surfaces of the positive electrode plate, the negative electrode plate, and the insulating layer breaks the insulating layer, causing electrical continuity between the positive electrode plate and the negative electrode plate, thereby causing an internal short circuit. Once an internal short circuit occurs, the Joule heat associated with the short circuit current may destroy the battery cell. On the other hand, even when an internal short circuit occurs in a battery cell, in order to ensure the safety of the battery cell, it is important to correctly evaluate the safety of the battery cell when the internal short circuit occurs. An example of the evaluation test is a nail penetration test. In the nail penetration test, a nail is pierced into the battery cell from the outside, the positive electrode plate and the negative electrode plate are short-circuited by the nail, and changes in temperature, voltage, etc. of the battery cell caused by Joule heat generated are measured (see, for example, patent documents 1).

WO 12/117660

In the nail penetration test, a nail must be stuck in a position that causes an internal short circuit. On the other hand, a battery module is configured by housing a plurality of battery cells in a housing. Moreover, a battery unit is configured by housing a plurality of battery modules in another housing. In such a battery unit or battery module, the battery cells are not exposed to the outside. Therefore, it becomes difficult to pierce a nail into a position that causes an internal short circuit.

The present disclosure has been made in view of such circumstances, and an object of the present disclosure is to provide a technique that facilitates internal short-circuiting of battery cells even in a structure in which a plurality of battery cells are housed.

In order to solve the above problems, a battery unit according to one aspect of the present disclosure includes a plurality of battery modules and an outer housing that accommodates the plurality of battery modules. Each of the plurality of battery modules includes a plurality of battery cells and an inner housing that houses the plurality of battery cells. The outer housing is an outer surface of the outer housing opposite to the interior of the outer housing in which the plurality of battery modules are arranged and facing the at least one battery cell. It has an outer recess with a concave shape. The inner housing of the battery module housing at least one battery cell is the inner surface of the outer side of the inner housing opposite to the interior of the inner housing in which the plurality of battery cells are arranged, and the at least one battery The inner surface facing the cell is provided with an inner recess having a shape recessed toward the inside. Each of the plurality of battery cells incorporates a positive electrode plate and a negative electrode plate, and the outer concave portion is provided with at least one through the inner housing when an object is inserted from the outer surface toward the inside of the outer housing. The outer recess is arranged at a position where the positive electrode plate and the negative electrode plate of the battery cell can be short-circuited by an object, and the outer concave portion has a first side surface having a tapered shape that tapers inward from the outer surface and an inner side end of the first side surface. and a first bottom surface that closes the inner recess, when an object is inserted from the outer recess toward the inside of the inner housing to short-circuit the positive electrode plate and the negative electrode plate of the at least one battery cell by the object, The inner recess is arranged at a position through which an object penetrates, and includes a second side surface having a tapered shape that tapers inward from the inner surface, and a second bottom surface that closes the inner side end of the second side surface.

According to the present disclosure, even in a structure in which a plurality of battery cells are housed, internal short-circuiting of the battery cells can be facilitated.

FIGS. 1(a) and 1(b) are diagrams showing the structure of a battery cell according to this embodiment. FIGS. 2(a) and 2(b) are diagrams showing structures of battery modules and battery units each including a plurality of battery cells shown in FIGS. 1(a) and 1(b). It is a figure which shows the structure of the battery unit which concerns on a present Example. 4(a) and 4(b) are diagrams showing the structures of the outer recess and the inner recess in FIG. FIG. 4 is a side view showing the structure of a battery module according to a modification;

Before specifically describing the embodiments of the present disclosure, an overview of the embodiments will be described. This embodiment relates to a battery unit. A plurality of battery modules are housed in the housing of the battery unit (hereinafter referred to as "outer housing"), and a plurality of battery cells are housed in the housing of each battery module (hereinafter referred to as "inner housing"). be. When the battery cell is a lithium ion secondary battery, an internal short circuit may occur between the positive electrode plate and the negative electrode plate due to destruction of the insulating layer due to conductor powder or shrinkage of the insulating layer at high temperatures. When an internal short circuit occurs between the positive electrode plate and the negative electrode plate, Joule heat associated with the short-circuit current expands the short-circuited portion and causes abnormal heating, which may result in the destruction of the battery cell. On the other hand, even when an internal short circuit occurs in a battery cell, it is important to prevent destruction of the battery cell and ensure safety. In order to ensure the safety of battery cells, it is necessary to correctly evaluate the safety of the battery when an internal short circuit occurs. For this reason, UL, JIS, SAE standards, etc. have established behavior evaluations for lithium-ion secondary batteries during internal short circuits. Various methods have been proposed for behavior evaluation during internal short circuits. For example, SAE J2464 describes an evaluation by a nail penetration test.

As described above, in the nail penetration test, a nail is pierced into the battery from the outside, the positive electrode plate and the negative electrode plate are short-circuited by the nail, and changes in temperature, voltage, etc. of the battery caused by Joule heat generation are measured. At that time, if the nail is stuck in a position where an internal short circuit does not occur, the nail penetration test cannot be performed accurately. Therefore, it is important to pierce the nail at a position that causes an internal short circuit. On the other hand, in the battery unit, multiple battery cells are housed inside the outer housing and the inner housing, so the battery cells are not exposed to the outside, making it difficult to stick a nail into a position that could cause an internal short circuit. Become. Furthermore, as the capacity of battery modules or battery units increases, the size of battery cells increases or the number of series increases. In this case, the influence of the destroyed battery cell on adjacent battery cells is more important than ever, so it is desirable to evaluate the final form.

In order to facilitate internal short-circuiting of the battery cells even in a structure in which a plurality of battery cells are housed, in this embodiment, the position where the internal short-circuit occurs in the battery cell (hereinafter referred to as "short-circuit position") is aligned in a straight line. Suppose an extended virtual nail is pierced. At the position where the imaginary nail intersects with the surface of the inner housing housing the battery cell (hereinafter referred to as the "inner surface"), an inner recess is provided that is recessed toward the inside of the inner housing. be done. Further, an outer recess having a shape recessed toward the inside of the outer housing is provided at a position where the virtual nail and the surface of the outer housing (hereinafter referred to as "outer surface") intersect. When a nail penetration test is performed, if a nail is pierced from the outer concave portion, the nail penetrates the outer concave portion and the inner concave portion to reach the short circuit position of the battery cell. Furthermore, even if the angle of the nail thrust through the outer recess is not toward the shorting position, the inner recess corrects the angle of the nail so that the nail is directed toward the shorting position. In the following description, "parallel" and "perpendicular" include not only perfectly parallel and perpendicular, but also deviate from parallel and perpendicular within a margin of error. Moreover, "substantially" means that they are the same within an approximate range.

1(a)-(b) show the structure of a battery cell 100. FIG. FIG. 1(a) is an external view of a battery cell 100. FIG. The battery cell 100 includes a first side 10 , a second side 12 , a third side 14 , a positive terminal 16 and a negative terminal 18 . The battery cell 100 has a cylindrical shape, the top surface of which is a circular first surface 10 , the side surface of which is a second surface 12 , and the bottom surface of which is a circular third surface 14 . Here, the combination of the first surface 10, the second surface 12 and the third surface 14 constitutes a case, which is made of steel, for example. A positive electrode terminal 16 that protrudes upward is disposed in the central portion of the first surface 10 . The third surface 14 is also the negative terminal 18 .

FIG. 1(b) is a cross-sectional view of the battery cell 100 perpendicular to the first surface 10 and the third surface 14. FIG. The battery cell 100 incorporates a positive electrode plate 50, a separator 60, and a negative electrode plate 70. The positive electrode plate 50, the separator 60, and the negative electrode plate 70 have a spiral structure wound in a spiral shape. For example, the positive electrode plate 50 uses lithium cobalt oxide as a main active material, and the negative electrode plate 70 uses special carbon as a main active material. Also, the separator 60 is an insulating layer impregnated with an electrolytic solution. In such a structure, the short circuit location is the location across the separator 60 and including the positive plate 50 and the negative plate 70, and is indicated as position P1, for example.

When assuming that a nail is stuck from the first surface 10 on which the positive electrode terminal 16 is provided, the position obtained by linearly moving the position P1 toward the first surface 10 is indicated as the position P2 on the first surface 10. . During a nail penetration test, when a nail is applied to position P2 on first surface 10 and advanced toward third surface 14, the nail reaches position P1. However, the direction in which the nail is stuck is not limited to the first surface 10 on which the positive electrode terminal 16 is provided, and may be the third surface 14 on which the negative electrode terminal 18 is provided, or the second surface 12 . In the following, as an example, as shown in FIG. 1B, the description will proceed on the premise that a nail is inserted from the first surface 10 on which the positive electrode terminal 16 is provided. Further, the short-circuit position is not limited to the position P1, and may be any position other than the position advanced from the central portion of the first surface 10 toward the third surface 14 and the position advanced toward the third surface 14 from the peripheral portion. .

2(a) and 2(b) show the structures of a battery module 200 and a battery unit 300 each including a plurality of battery cells 100. FIG. As shown in FIGS. 2(a)-(b), a Cartesian coordinate system is defined that includes x-, y-, and z-axes. The x-axis and y-axis are orthogonal to each other within the bottom surfaces of battery module 200 and battery unit 300 . The z-axis is perpendicular to the x-axis and the y-axis and extends in the height (vertical) direction of the battery modules 200 and battery units 300 . Also, the positive directions of the x-axis, y-axis, and z-axis are defined in the directions of the arrows in FIG. 1, and the negative directions are defined in directions opposite to the arrows. In addition, the positive side of the x-axis is the "front side", the negative side of the x-axis is the "rear side", the positive side of the z-axis is the "upper side" or the "top side", and the negative direction of the z-axis is the "side". Also referred to as "lower side" or "bottom side". Furthermore, the positive side of the y-axis is sometimes called the "right side", and the negative side of the y-axis is sometimes called the "left side".

FIG. 2(a) shows the structure of the cross section of the yz plane at a position near the front end of the battery module 200 as seen from the front side. As shown, the battery module 200 includes first battery cells 100 a to eleventh battery cells 100 k and an inner housing 110 , collectively referred to as battery cells 100 . The number of battery cells 100 included in battery module 200 is not limited to "11". The inner housing 110 has a hollow box shape elongated in the front-rear direction, and is surrounded by first to sixth inner surfaces 120a to 120f, collectively referred to as inner surfaces 120 . In FIG. 2(a), the first inner surface 120a and the second inner surface 120b are omitted.

Specifically, the inner housing 110 has a third inner surface 120c on the top, a fourth inner surface 120d on the bottom, a fifth inner surface 120e on the left, and a fifth inner surface 120e on the right. is disposed on the sixth inner surface 120f. Further, a first inner surface 120a is arranged on the front side of the inner housing 110, and a second inner surface 120b is arranged on the rear side. The first inner surface 120a through the sixth inner surface 120f are all rectangular. In particular, two opposing inner surfaces 120 have the same shape. The shape of inner housing 110 and inner surface 120 is not limited to this.

A plurality of battery cells 100 are housed inside the inner housing 110 . Here, the plurality of battery cells 100 are arranged with the first surface 10 facing forward. At that time, the first surface 10 of the battery cell 100 and the first inner surface 120a are separated by a predetermined distance. Wiring for connecting the plurality of battery cells 100 and circuits for executing control over the plurality of battery cells 100 are also included in the battery module 200, but are omitted here.

FIG. 2(b) shows the structure of the cross section of the zx plane at a position near the leftmost end of the battery unit 300 as viewed from the left. As shown, the battery unit 300 includes first battery modules 200 a to third battery modules 200 c , collectively referred to as battery modules 200 , and an outer housing 210 . The number of battery modules 200 included in battery unit 300 is not limited to "3". Here, as an example, three battery modules 200 are vertically stacked, so the outer housing 210 has a vertically elongated hollow box shape, and a first outer surface 220a collectively referred to as the outer surface 220. to the sixth outer surface 220f. In FIG. 2(b), the fifth outer surface 220e and the sixth outer surface 220f are omitted.

Specifically, the outer housing 210 has a first outer surface 220a on the front side, a second outer surface 220b on the rear side, a third outer surface 220c on the top side, and a third outer surface 220c on the bottom side. is disposed on the fourth outer surface 220d. Furthermore, a fifth outer surface 220e is arranged on the left side of the outer housing 210, and a sixth outer surface 220f is arranged on the right side. In particular, the two opposing outer surfaces 220 have the same shape. The shape of outer housing 210 and outer surface 220 is not limited to this.

A plurality of battery modules 200 are housed inside the outer housing 210 . At that time, the first inner surface 120a and the first outer surface 220a of the battery module 200 are separated by a predetermined distance. Wiring for connecting the plurality of battery modules 200 and circuits for executing control over the plurality of battery modules 200 are also included in the battery unit 300, but are omitted here.

As described above, a plurality of battery cells 100 are housed inside the inner housing 110 of the battery module 200, but when the battery unit 300 is viewed from the outside, the plurality of battery cells 100 are not exposed. Further, the first surface 10 and the first inner surface 120a of the battery cell 100 are spaced apart, and the first inner surface 120a and the first outer surface 220a are also spaced apart, so that the first surface 10 of the battery cell 100 is spaced apart from the first outer surface. 220a. Combining these situations, when performing a nail penetration test on at least one of the plurality of battery cells 100 housed in the battery unit 300, even if a nail is pierced from the first outer surface 220a, It can be said that the possibility of the nail reaching the position P2 of the first surface 10 is low. In order to improve this possibility, the battery module 200 and the battery unit 300 according to this embodiment further have the following structure.

FIG. 3 shows the structure of the battery unit 300. As shown in FIG. This is a cross-sectional view in the zx plane. Here we will focus on the differences. As an example, the eighth battery cell 100h in the lowest third battery module 200c is subjected to the nail penetration test. As shown in FIG. 2(a), the eighth battery cell 100h is the battery cell 100 arranged at the bottom and left end. As shown, the positions P1 and P2 of the eighth battery cell 100h are aligned in the front-rear direction, and the position P2 is arranged on the first surface 10 of the eighth battery cell 100h.

The first inner surface 120a of the inner housing 110 is provided with an inner recess 130 that is recessed toward the inside of the inner housing 110 . The inner recess 130 is arranged in a portion of the first inner surface 120a facing the first surface 10 of the eighth battery cell 100h. In particular, the inner recessed portion 130 is arranged at positions P1 and P2 aligned in the front-rear direction. Further, the first outer surface 220 a of the outer housing 210 is provided with an outer concave portion 230 that is recessed toward the inside of the outer housing 210 . The outer recessed portion 230 is arranged in a portion of the first outer surface 220a that faces the first surface 10 of the eighth battery cell 100h via the first inner surface 120a. In particular, the outer recessed portion 230 is arranged at a position aligned with the position P1, the position P2, and the inner recessed portion 130 in the front-rear direction.

In FIG. 3 the aforementioned nail or virtual nail is indicated as conductor 400 . Under this definition, when the conductor 400 is inserted from the first outer surface 220a toward the inside of the outer housing 210, the outer recess 230 passes through the inner housing 110 to the positive electrode plate of the eighth battery cell 100h. 50 and the negative electrode plate 70 can be said to be arranged at a position where the conductor 400 can be short-circuited. In addition, when the conductor 400 is inserted into the inner recess 130 from the inner recess 130 toward the inside of the inner housing 110 to short-circuit the positive electrode plate 50 and the negative electrode plate 70 of the eighth battery cell 100h by the conductor 400, It can be said that it is arranged at a position through which the conductor 400 penetrates. Therefore, the examiner of the nail penetration test simply applies the tip of the conductor 400 to the outer concave portion 230 and moves the conductor 400 to the rear side, and the conductor 400 passes through the outer concave portion 230, the inner concave portion 130, and the position P2. Position P1 is reached. As a result, the eighth battery cell 100h is short-circuited by the conductor 400. FIG.

On the other hand, if the direction of movement of the conductor 400 whose tip is in contact with the outer recess 230 deviates from the rear side, the conductor 400 may not pass through the inner recess 130, position P2. 4(a) and 4(b) are used here to explain the structures of the outer recess 230 and the inner recess 130 for corresponding to this. 4(a)-(b) show the structure of the outer recess 230 and the inner recess 130. FIG. FIG. 4(a) is an enlarged cross-sectional view of the vicinity of the outer concave portion 230 of FIG. Outer recess 230 includes side surfaces 232 and bottom surface 234 . The side surface 232 has a circular opening on the first outer surface 220a and has a tapered shape that narrows rearward from the first outer surface 220a. A circular bottom surface 234 is arranged at the rear end of the side surface 232 . With this structure, when the tip of conductor 400 is not angled rearward, the tip of conductor 400 contacts side surface 232 instead of bottom surface 234 . Conductor 400 in contact with side 232 moves toward bottom 234 due to the slope of side 232 . Conductor 400 that reaches bottom surface 234 passes through bottom surface 234 and moves inside outer housing 210 . Therefore, the angle of the tip of the conductor 400 is corrected to face rearward.

FIG. 4(b) is a cross-sectional view enlarging the vicinity of the inner concave portion 130 of FIG. Inner recess 130 includes sides 132 , 132 . Side 132 and bottom 134 have the same shape as side 232 and bottom 234 . Here, the size of the side surface 132 and the bottom surface 134 may be the same as or different from the size of the side surface 232 and the bottom surface 234 . With such a structure, if the direction of movement of the conductor 400 passing through the outer recess 230 deviates from the rear side, the tip of the conductor 400 contacts the side surface 132 instead of the bottom surface 134 . Conductor 400 in contact with side 132 moves toward bottom 134 due to the slope of side 132 . The conductor 400 that has reached the bottom surface 134 penetrates the bottom surface 134 and moves inside the inner housing 110 . Return to FIG. As a result, conductor 400 passes through position P2 and reaches position P1.

The battery cell 100 and the battery module 200 to be subjected to the nail penetration test will be described below. When a plurality of battery cells 100 are arranged in the inner housing 110 as shown in FIG. . For example, the number of neighbors in the first battery cell 100a, the fourth battery cell 100d, the eighth battery cell 100h, and the eleventh battery cell 100k is "3". The number of neighbors in the second battery cell 100b, the third battery cell 100c, the ninth battery cell 100i, and the tenth battery cell 100j is "4". The number of neighbors in the fifth battery cell 100e and the seventh battery cell 100g is "5". The number of neighbors in the sixth battery cell 100f is "6".

As mentioned above, the case of the battery cell 100 is made of steel. Also, it is assumed that the inner housing 110 is made of a material such as resin that has a lower thermal conductivity than metal such as steel. Under such circumstances, the heat generated in the battery cells 100 with a large number of neighbors escapes to the adjacent battery cells 100 more easily than the heat generated in the battery cells 100 with a small number of neighbors. When a nail penetration test is performed on the sixth battery cell 100f, the heat generated from the sixth battery cell 100f easily escapes, so the influence of heat generation is reduced. On the other hand, when a nail penetration test is performed on the eighth battery cell 100h, the heat generated from the eighth battery cell 100h is difficult to escape, so the influence of heat generation is difficult to reduce. Therefore, it can be said that a battery cell 100 with a smaller number of adjacent cells is more suitable for a nail penetration test. It can be said that a battery cell 100 having a larger area facing the inner housing 110 is more suitable for a nail penetration test.

Next, it is assumed that, in a structure in which a plurality of battery modules 200 are vertically arranged in an outer housing 210 as shown in FIG. 2B, one of the battery modules 200 burns due to heat generation. Since the flame from the battery module 200 is directed upward, the possibility of the fire spreading to another battery module 200 placed above the battery module 200 is higher than that of the battery module 200 placed below the battery module 200 . That is, the lower the battery module 200 that burns due to heat generation, the greater the damage caused by the spread of fire. Therefore, it can be said that the lower the battery module 200 is arranged, the more suitable it is to be subjected to the nail penetration test. In the structure of FIG. 2(b), the third battery module 200c is most suitable for the nail penetration test.

An inner recess 130 and an outer recess 230 are provided so as to face the battery cells 100 of the battery module 200 selected in this way. Moreover, the number of battery cells 100 to be subjected to the nail penetration test may not be one, and may be plural. In that case, a plurality of inner recesses 130 and a plurality of outer recesses 230 are provided.

According to this embodiment, when the conductor 400 is inserted from the outer surface 220 toward the inside, the outer recess 230 is arranged at a position where the battery cells 100 can be internally short-circuited. In terms of structure, the internal short circuit of the battery cell 100 can also be facilitated. Further, since the outer recess 230 includes the side surface 232 and the bottom surface 234 , even if the direction of the tip of the conductor 400 faces the side surface 232 , the direction of the tip of the conductor 400 can be corrected toward the bottom surface 234 . In addition, since the direction of the tip of the conductor 400 is corrected toward the bottom surface 234, internal short-circuiting of the battery cell 100 can be facilitated.

In addition, when the conductor 400 is inserted from the outer recess 230 toward the inside to internally short-circuit the battery cell 100, the inner recess 130 is arranged at the position where the conductor 400 penetrates, so that a structure in which a plurality of battery cells 100 are accommodated. Also, the battery cell 100 can be easily short-circuited internally. Also, since the inner recess 130 includes the side surface 132 and the bottom surface 134 , even if the direction of the tip of the conductor 400 faces the side surface 132 , the direction of the tip of the conductor 400 can be corrected toward the bottom surface 134 . In addition, since the direction of the tip of the conductor 400 is corrected toward the bottom surface 134, the internal short circuit of the battery cell 100 can be easily caused.

Moreover, since the battery cells 100 having a small number of adjacent battery cells 100 are subjected to the nail penetration test and the inner concave portion 130 and the outer concave portion 230 are provided, the accuracy of the test result can be improved. Further, since the inner recess 130 and the outer recess 230 are provided for the battery cells 100 included in the battery module 200 arranged on the lower side as targets of the nail penetration test, the precision of the test results can be improved.

A summary of one aspect of the present disclosure is as follows. A battery module 200 according to an aspect of the present disclosure includes multiple battery cells 100 and an inner housing 110 that houses the multiple battery cells 100 . The inner housing 110 includes an inner recess 130 having a shape recessed toward the inside on the inner surface 120 facing at least one battery cell 100 . Each of the plurality of battery cells 100 incorporates a positive electrode plate 50 and a negative electrode plate 70, and the inner recess 130 allows at least one battery cell to be inserted into the inner housing 110 from the inner surface 120 when an object is inserted. The positive electrode plate 50 and the negative electrode plate 70 of the cell 100 are arranged at a position where an object can short-circuit the positive electrode plate 50 and the negative electrode plate 70 .

The object is the conductor 400, and the inner recess 130 is positioned inside the at least one battery cell 100 when inserting the conductor 400 from the inner surface 120 toward the inside of the inner housing 110. The plate 50 and the negative electrode plate 70 may be arranged at positions where they can be short-circuited by the conductor 400 .

Another aspect of the disclosure is the battery unit 300 . This battery unit 300 includes a plurality of battery modules 200 and an outer housing 210 that houses the plurality of battery modules 200 . Each of the multiple battery modules 200 includes multiple battery cells 100 and an inner housing 110 that houses the multiple battery cells 100 . The outer housing 210 includes an inwardly recessed outer recess 230 on an outer surface 220 facing at least one battery cell 100 . Each of the plurality of battery cells 100 incorporates a positive electrode plate 50 and a negative electrode plate 70, and the outer concave portion 230 is a portion of the inner housing 110 when an object is inserted from the outer surface 220 toward the inside of the outer housing 210. The positive electrode plate 50 and the negative electrode plate 70 of at least one battery cell 100 are arranged at a position where an object can short-circuit the positive electrode plate 50 and the negative electrode plate 70 of the at least one battery cell 100 via the .

The inner housing 110 of the battery module 200 that houses at least one battery cell 100 may further include an inner recess 130 that is recessed toward the inside on the inner surface 120 that faces the at least one battery cell 100. . When an object is inserted from the outer recess 230 toward the inside of the inner housing 110 to short-circuit the positive electrode plate 50 and the negative electrode plate 70 of at least one battery cell 100 with the object, the object penetrates the inner recess 130 . is placed in the position where

The object is a conductor 400, and the outer recess 230 extends into the at least one battery cell 100 through the inner housing 110 when inserting the conductor 400 from the outer surface 220 toward the interior of the outer recess 230. , the positive electrode plate 50 and the negative electrode plate 70 of the battery cell 100 may be arranged at positions where the conductor 400 can short-circuit the positive electrode plate 50 and the negative electrode plate 70 .

The present disclosure has been described above based on the embodiments. It should be understood by those skilled in the art that this embodiment is an example, and that various modifications are possible in the combination of each component or each treatment process, and such modifications are within the scope of the present disclosure. .

In this embodiment, the inner surface 120 is provided with an inner recess 130 and the outer surface 220 is provided with an outer recess 230 . However, for example, the outer surface 220 may be provided with the outer recess 230 , but the inner surface 120 may not be provided with the inner recess 130 . According to this modified example, the structure can be simplified.

In this embodiment, the battery cells 100 included in the battery unit 300 are subjected to the nail penetration test. However, not limited to this, for example, the battery cells 100 included in the battery module 200 may be subjected to the nail penetration test. According to this modified example, the scope of application of the present embodiment can be expanded.

In this embodiment, the inner recess 130 has a shape that is recessed from the inner surface 120 toward the inside of the inner housing 110 . However, for example, the inner recess 130 may have a tunnel shape extending from the inner surface 120 toward the inside of the inner housing 110 . FIG. 5 shows the structure of the battery cell 100. As shown in FIG. As an example, the inner recess 130 extends from the sixth inner surface 120f, passes between the fourth battery cell 100d, the third battery cell 100c, and the seventh battery cell 100g, and bends toward the sixth battery cell 100f. have a shape. In this case, as conductor 400 an instrument with a bendable tip is used. According to this modified example, the degree of freedom in configuration can be improved.

In this embodiment, an internal short circuit is generated by sticking a nail-like conductor 400 into the battery cell 100 . However, not limited to this, for example, by locally pressing the second surface 12 of the battery cell 100 with an object, the distance between the positive electrode plate 50 and the negative electrode plate 70 may be narrowed to cause an internal short circuit. In this case, the object does not have to be a conductor 400 such as a nail, as long as it has enough strength to penetrate the inner recess 130 or the outer recess 230 . According to this modified example, the degree of freedom in configuration can be improved.

REFERENCE SIGNS LIST 10 first surface 12 second surface 14 third surface 16 positive terminal 18 negative terminal 50 positive plate 60 separator 70 negative plate 100 battery cell 110 inner housing (housing) 120 inner surface (surface), 130 inner recess (recess), 132 side surface, 134 bottom surface, 200 battery module, 210 outer housing, 220 outer surface, 230 outer recess surface, 232 side surface, 234 bottom surface, 300 battery unit, 400 conductor (object).

Claims (2)

a plurality of battery modules;
an outer housing for housing the plurality of battery modules,
each of the plurality of battery modules,
a plurality of battery cells;
An inner housing that houses the plurality of battery cells,
The outer housing is an outer surface of the outer housing opposite to the interior of the outer housing in which the plurality of battery modules are arranged, and the outer surface facing at least one battery cell. , with an outer recess having a concave shape towards the inside,
The inner housing of the battery module housing the at least one battery cell is an outer inner surface of the inner housing opposite to the interior of the inner housing where the plurality of battery cells are arranged. and an inner recess having a shape recessed toward the inside on the inner surface facing the at least one battery cell,
each of the plurality of battery cells includes a positive electrode plate and a negative electrode plate;
When an object is inserted from the outer surface toward the inside of the outer housing, the outer recess allows the positive electrode plate and the negative electrode plate of the at least one battery cell to be pushed through the inner housing by the object. placed in a position where a short circuit is possible,
The outer recess includes a first side surface having a tapered shape that tapers inward from the outer surface, and a first bottom surface that closes the inner side end of the first side surface,
When the object is inserted from the outer recess toward the inside of the inner housing to short-circuit the positive electrode plate and the negative electrode plate of the at least one battery cell by the object, the object is inserted into the inner recess. It is placed in a position to be penetrated,
The inner recess includes a second side surface having a tapered shape that narrows inward from the inner surface, and a second bottom surface that closes the inner side end of the second side surface.
battery unit. the object is a conductor,
When the conductor is inserted from the outer surface toward the inside of the outer housing, the outer concave portion is positioned inside the at least one battery cell through the inner housing when the positive electrode plate of the battery cell is inserted. and the negative electrode plate are arranged at a position where they can be short-circuited by the object,
The battery unit according to claim 1 .

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