阅读说明：本技术 蓄电装置 (Electricity storage device ) 是由 松下太朗 近藤忠宏 石川翔太朗 岸甲一朗 渡边健太 于 2021-06-02 设计创作，主要内容包括：蓄电装置(100)具备蓄电堆(110)和收容壳体(140)。在蓄电堆(110)中,沿着第一方向(DR1)交替层叠有多个单元电池(120)和多个间隔件(130)。在多个间隔件(130)的每一个中,第一支承面(131)与在第一方向(DR1)的一侧相邻的单元电池(120)的第一锥面(121)对应地倾斜并与第一锥面(121)接触。在多个间隔件(130)的每一个中,第二支承面(132)与在第一方向(DR1)的另一侧相邻的单元电池(120)的第二锥面(122)对应地倾斜并与第二锥面(122)接触。多个间隔件(130)的每一个由热塑性树脂构成。(The power storage device (100) is provided with a power storage stack (110) and a housing case (140). In the electricity storage stack (110), a plurality of unit cells (120) and a plurality of spacers (130) are alternately stacked along a first direction (DR 1). In each of the plurality of spacers (130), the first support surface (131) is inclined corresponding to the first tapered surface (121) of the unit cell (120) adjacent to one side in the first direction (DR1) and is in contact with the first tapered surface (121). In each of the plurality of spacers (130), the second support surface (132) is inclined corresponding to the second taper surface (122) of the unit cell (120) adjacent to the other side of the first direction (DR1) and is in contact with the second taper surface (122). Each of the plurality of spacers (130) is composed of a thermoplastic resin.)

1. An electricity storage device is provided with:

a power storage stack in which a plurality of unit cells and a plurality of spacers are alternately stacked in a first direction; and

a housing case that houses the electricity storage stack,

the electricity storage stack is restrained in the housing case in the first direction,

each of the plurality of unit cells has a first tapered surface and a second tapered surface that are inclined so as to become gradually smaller in interval with each other toward one of second directions intersecting the first direction, and that constitute both end surfaces in the first direction,

each of the plurality of spacers has a first support surface and a second support surface that constitute both end surfaces in the first direction,

in each of the plurality of spacers, the first support surface is inclined corresponding to and in contact with the first tapered surface of the unit cell adjacent to one side in the first direction,

in each of the plurality of spacers, the second support surface is inclined corresponding to and in contact with the second taper surface of the unit cell adjacent to the other side of the first direction,

each of the plurality of spacers is composed of a thermoplastic resin.

2. The power storage device according to claim 1,

the electricity storage stack has a first end face and a second end face that constitute both end faces in the first direction,

the first end surface of the electricity storage stack is constituted by the first tapered surface of the unit cell arranged on one end side in the first direction,

the second end surface of the electricity storage stack is constituted by the second taper surface that the unit cell arranged on the other end side in the first direction has,

the housing case has a first inner side surface and a second inner side surface opposed to each other in the first direction,

the first inner side surface includes a first inclined portion inclined correspondingly to the first tapered surface,

the second inner side surface includes a second inclined portion inclined correspondingly to the second taper surface,

the electricity storage stack is held by the housing case in a state where the first end surface is in contact with the first inclined portion and the second end surface is in contact with the second inclined portion.

3. The power storage device according to claim 1 or 2,

a cooler disposed between the bottom of the housing case and the power storage stack to cool the plurality of unit cells,

the bottom portion is opposed to the power storage stack from the one side in the second direction,

each of the plurality of spacers is positioned in the second direction by contact with the cooler.

4. The power storage device according to claim 1 or 2,

the housing case has a bottom portion opposed to the power storage stack from the one side in the second direction,

each of the plurality of spacers is positioned in the second direction by being in contact with the bottom.

Technical Field

The present disclosure relates to a power storage device mounted on a vehicle.

Background

As a document disclosing the structure of the power storage device, japanese patent application laid-open No. 2018-32519. The power storage device described in japanese patent application laid-open No. 2018-32519 is a battery module, and includes a cell stack and a housing case. The cell stack includes a cell stack body in which a plurality of rectangular parallelepiped cells are stacked in a thickness direction, and a pair of end plates. The pair of end plates are disposed at both ends of the cell stack in the stacking direction. At least one of the pair of end plates has a stack-side facing surface that is inclined such that a dimension in the stacking direction of the cell stack decreases as the cell stack approaches the lower end of the housing case. The housing space has a housing-side opposed surface inclined so that the dimension of the housing space in the stacking direction becomes smaller. Since the stack side facing surface and the case side facing surface facing each other are inclined, respectively, a restraining load can be applied to the stack by pressing the stack into the housing space.

Disclosure of Invention

As in the power storage device disclosed in japanese patent application laid-open No. 2018-32519, the power storage stack in the conventional power storage device is subjected to a restraining load, and therefore heat is easily transmitted to each other among the plurality of unit cells included in the power storage stack. Therefore, when one of the plurality of unit cells abnormally generates heat, the heat is transferred from the abnormally generated unit cell to the other unit cells. The other unit cells may also generate heat abnormally as the other unit cells are heated. As described above, in the conventional power storage device, a chain reaction of heat generation of the plurality of unit cells may occur.

The present invention has been made in view of the above problems, and an object thereof is to provide an electric storage device capable of suppressing heat conduction from one of a plurality of unit cells to another unit cell when the unit cell abnormally generates heat in an electric storage stack.

The power storage device according to the present disclosure includes a power storage stack and a housing case. In the electricity storage stack, a plurality of unit cells and a plurality of spacers are alternately stacked in a first direction. The housing case houses the accumulator stack. The electricity storage stack is constrained in the housing case in the first direction. Each of the plurality of unit cells has a first tapered surface and a second tapered surface. The first tapered surface and the second tapered surface are inclined so that the distance therebetween gradually decreases toward one of second directions intersecting the first direction, and form both end surfaces of the unit cell in the first direction. Each of the plurality of spacers has a first bearing surface and a second bearing surface. The first support surface and the second support surface constitute both end surfaces of the spacer in the first direction. In each of the plurality of spacers, the first support surface is inclined corresponding to and in contact with the first tapered surface of the unit cell adjacent to one side in the first direction. In each of the plurality of spacers, the second support surface is inclined correspondingly to and in contact with the second taper surface of the unit cell adjacent to the other side in the first direction. Each of the plurality of spacers is composed of a thermoplastic resin.

A frictional force is generated between the tapered surfaces of the unit cells and the support surfaces of the spacers made of thermoplastic resin. This can suppress displacement of the unit cell in the second direction due to the restraining force acting on the battery stack. Further, the accumulator stack can be maintained in a state of being subjected to the restraining force. Further, when any of the plurality of unit cells abnormally generates heat, the support surface of the spacer made of thermoplastic resin adjacent to the unit cell that generates heat is thermally deformed. This reduces the coefficient of friction between the support surface of the spacer and the tapered surface of the cell. The heat-generating unit cells receive the restraining force and are displaced in the second direction while sliding on the support surfaces of the spacers. The binding force is reduced by the displacement of the heat-generating unit cells. Since the binding force is reduced, heat conduction from the abnormally heated cell to the other cells in the power storage stack can be suppressed.

In the power storage device according to one aspect of the present disclosure, the power storage stack has a first end surface and a second end surface. The first end face and the second end face constitute both end faces of the electricity storage stack in the first direction. The first end surface of the electricity storage stack is formed of a first tapered surface of the unit cell arranged on one end side in the first direction. The second end surface of the power storage stack is configured by a second tapered surface provided in the unit cell arranged on the other end side in the first direction. The accommodating shell is provided with a first inner side surface and a second inner side surface. The first inner side surface and the second inner side surface are opposite to each other in the first direction. The first inner side surface includes a first inclined portion. The first inclined portion is inclined corresponding to the first tapered surface. The second inner side surface includes a second inclined portion. The second inclined portion is inclined correspondingly to the second taper surface. The power storage stack is held by the housing case in a state where the first end surface is in contact with the first inclined portion and the second end surface is in contact with the second inclined portion.

Thus, the power storage stack can be held in the storage case without providing another member such as an end plate between the end surface of the power storage stack in the first direction and the inner surface of the storage case.

The power storage device according to one aspect of the present disclosure further includes a cooler. The cooler is disposed between the bottom of the housing case and the power storage stack. The cooler cools the plurality of unit batteries. The bottom portion is opposed to the power storage stack from one side in the second direction. Each of the plurality of spacers is positioned in the second direction by contact with the cooler.

In this way, by positioning the plurality of spacers in the second direction, the position of the entire electrical storage stack in the second direction is stabilized. Further, the reliability of the power storage device is improved.

In the power storage device according to one aspect of the present disclosure, the housing case has a bottom portion. The bottom portion is opposed to the power storage stack from one side in the second direction. Each of the plurality of spacers is positioned in the second direction by contacting the bottom.

In this way, by positioning the plurality of spacers in the second direction, the position of the entire electrical storage stack in the second direction is stabilized. Further, the reliability of the power storage device is improved.

Drawings

The above and other objects, features, aspects and advantages of the present disclosure will become apparent from the following detailed description of the present disclosure, which is to be read in connection with the accompanying drawings.

Fig. 1 is a schematic diagram showing a vehicle including a power storage device according to embodiment 1.

Fig. 2 is a schematic plan view of the power storage device according to embodiment 1.

Fig. 3 is a schematic cross-sectional view of the power storage device of fig. 2 viewed in the direction of the arrow on the line III-III.

Fig. 4 is a cross-sectional view showing a state in which a plurality of cells and a plurality of spacers are arranged in the housing case with one cell removed in embodiment 1.

Fig. 5 is a cross-sectional view showing a state in which a plurality of unit cells and a plurality of spacers are arranged in a housing case excluding one unit cell, and the remaining unit cells are press-fitted in order to form a battery stack in embodiment 1.

Fig. 6 is a schematic cross-sectional view showing forces acting on the unit cells in the power storage device according to embodiment 1.

Fig. 7 is a schematic cross-sectional view showing a no-load state of the battery stack in embodiment 1.

Fig. 8 is a schematic cross-sectional view of the power storage device in embodiment 1 showing a state in which the abnormally heated unit cells are displaced.

Fig. 9 is a cross-sectional view schematically showing the power storage stack in embodiment 1 in a state where the power storage stack is in an unloaded state in the first direction while maintaining the displacement of the abnormally heated unit cell in the second direction.

Fig. 10 is a schematic cross-sectional view of a power storage device according to embodiment 2.

Detailed Description

Hereinafter, a power storage device according to each embodiment will be described with reference to the drawings. In the following description of the embodiments, the same or corresponding portions in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated.

(embodiment mode 1)

Fig. 1 is a schematic diagram showing a vehicle including a power storage device according to embodiment 1. Referring to fig. 1, a vehicle 1 including a power storage device 100 according to embodiment 1 will be described.

Vehicle 1 includes vehicle body 2, drive device 3, front wheels 5, rear wheels 6, and power storage device 100. An engine room, a boarding space, and a luggage room are formed in the vehicle body 2. The engine room is formed on the front side of the vehicle 1, and the boarding space is formed behind the engine room. The luggage room is formed behind the boarding space.

The drive device 3 is housed in the engine room. The drive device 3 includes a rotating electric machine 7 and a pcu (powercontrol) 8. The PCU8 includes an inverter and a converter. PCU8 is electrically connected to power storage device 100 and rotating electric machine 7.

PCU8 boosts the voltage of the dc power supplied from power storage device 100, converts the boosted voltage into ac power, and supplies the ac power to rotating electric machine 7.

The rotating electrical machine 7 generates a driving force for rotating the front wheels 5 using ac power supplied from the PCU 8. The vehicle 1 is an electric vehicle such as an electric vehicle or a hybrid vehicle.

Next, power storage device 100 will be described. Fig. 2 is a schematic plan view of the power storage device according to embodiment 1. Fig. 3 is a schematic cross-sectional view of the power storage device of fig. 2 viewed in the direction of the arrow on the line III-III. As shown in fig. 2 and 3, power storage device 100 according to embodiment 1 includes power storage stack 110, storage case 140, and cooler 190.

As shown in fig. 2 and 3, in the battery stack 110, the plurality of unit cells 120 and the plurality of spacers 130 are alternately stacked in the first direction DR 1. The housing case 140 houses the accumulator stack 110. The receiving case 140 includes a lower case 150 and an upper case 160.

The power storage stack 110 is constrained in the first direction DR1 within the housing case 140. That is, the battery stack 110 receives the restraining load in the first direction DR 1. By restraining the battery stack 110 in the first direction DR1, the positions of the unit cells 120 and the spacers 130 are limited, thereby improving the reliability of the battery stack 110. Details of the above-described restraining load will be described later.

Specifically, the first direction DR1 is a horizontal direction. Although the power storage device 100 according to the present embodiment illustrates the case where the first direction DR1 is the front-rear direction of the vehicle 1, the first direction DR1 may be the width direction of the vehicle 1.

As shown in fig. 3, the electricity storage stack 110 has a first end face 111 and a second end face 112. The first end surface 111 and the second end surface 112 constitute both end surfaces of the electricity storage stack 110 in the first direction DR 1.

In the present embodiment, a single cell, for example, may be used as each of the plurality of unit cells 120. The battery cell is, for example, a secondary battery such as a nickel-metal hydride battery or a lithium ion battery. The single cell has, for example, a square shape. The secondary battery may be a secondary battery using a liquid electrolyte, or a secondary battery using a solid electrolyte. The unit cell 120 may be a unit capacitor configured to be chargeable and dischargeable.

Each of the plurality of unit cells 120 is electrically connected in series with each other within the receiving case 140. In fig. 2, 3, and subsequent figures, the structure for electrically connecting the plurality of unit cells 120 to each other is not shown.

As described above, each of the plurality of unit cells 120 is a so-called prismatic battery, but each of the plurality of unit cells 120 has a quadrangular shape in which both end faces in the first direction DR1 are inclined. Each unit cell 120 has a first tapered surface 121 and a second tapered surface 122. The first tapered surfaces 121 and the second tapered surfaces 122 constitute both end surfaces of the unit cells 120 in the first direction DR 1. The first tapered surface 121 and the second tapered surface 122 are inclined so that the interval therebetween becomes smaller toward one of the second directions DR2 intersecting the first direction DR 1.

In the present embodiment, the second direction DR2 is orthogonal to the first direction DR 1. The second direction DR2 is specifically a vertical direction. One of the second directions DR2 is specifically a lower direction, and the other of the second directions DR2 is specifically an upper direction.

The first tapered surface 121 has a rectangular outer shape when viewed from a direction orthogonal to the first tapered surface 121. The second tapered surface 122 has a rectangular outer shape when viewed from a direction orthogonal to the second tapered surface 122. In addition, each of the plurality of unit cells 120 has upper and lower surfaces intersecting the second direction. The upper and lower surfaces of each of the plurality of unit cells 120 have a rectangular outer shape.

The first end surface 111 of the power storage stack 110 is formed by the first tapered surface 121 of the unit cell 120 disposed on one end side in the first direction DR 1. The second end surface 112 of the power storage stack 110 is constituted by the second taper surface 122 provided to the unit cell 120 arranged on the other end side in the first direction DR 1.

As shown in fig. 3, each of the plurality of spacers 130 has a first bearing surface 131 and a second bearing surface 132. The first support surface 131 and the second support surface 132 constitute both end surfaces of the spacer 130 in the first direction DR 1.

In each of the plurality of spacers 130, the first supporting surface 131 is inclined corresponding to the first taper surface 121 of the unit cell 120 adjacent to one side of the first direction DR1 and contacts the first taper surface 121. In each of the plurality of spacers 130, the second supporting surface 132 is inclined corresponding to the second taper surface 122 of the unit cell 120 adjacent to the other side of the first direction DR1 and contacts the second taper surface 122. For ease of explanation, fig. 2 and 3 schematically illustrate the members adjacent to each other in the first direction DR1 while being separated from each other.

In the present embodiment, each of the plurality of spacers 130 is not coupled to each other, but is located at a position separated from each other. Each of the plurality of spacers 130 may be interconnected in the housing case 140, but in this case, as described later, it is preferable that each of the plurality of spacers 130 is configured to be displaceable in the first direction DR1 when the unit cell 120 is displaced in the second direction DR 2.

Each of the plurality of spacers 130 is composed of a thermoplastic resin such that, when the adjacent unit cell 120 abnormally generates heat, a portion of the first supporting surface 131, which is in contact with the first tapered surface 121 of the unit cell 120, and a portion of the second supporting surface 132, which is in contact with the second tapered surface 122 of the unit cell 120, can be thermally deformed. The functional function of the spacer 130 when the thermal deformation occurs will be described later.

The housing case 140 houses the accumulator stack 110. The housing case 140 may house a plurality of the accumulator stacks 110. The housing case 140 is made of a metal material such as aluminum.

The lower case 150 (the accommodation case 140) has a first inner side surface 151, a second inner side surface 152, and a bottom 153. First medial side 151 and second medial side 152 oppose each other in first direction DR 1.

The first inner surface 151 includes a first inclined portion 151 a. The first inclined portion 151a is inclined corresponding to the first tapered surface 121 of the cell 120 disposed on one end side in the first direction DR 1. The first inclined portion 151a may constitute only a part of the first inner surface 151, or may constitute the entire first inner surface 151.

The second inner side surface 152 includes a second inclined portion 152 a. The second inclined portion 152a is inclined in correspondence to the second taper surface 122 of the unit cell 120 disposed on the other end side in the first direction DR 1. The second inclined portion 152a may constitute only a part of the second inner surface 152, or may constitute the entire second inner surface 152.

The power storage stack 110 is held by the housing case 140 in a state where the first end surface 111 is in contact with the first inclined portion 151a and the second end surface 112 is in contact with the second inclined portion 152 a.

The bottom 153 of the housing case 140 faces the power storage stack 110 from one (lower) side in the second direction DR 2. In the present embodiment, the electricity storage stack 110 and the bottom 153 are separated from each other.

The lower housing 150 has an opening 154 on the opposite side of the bottom 153. The upper case 160 closes the opening 154.

The cooler 190 is disposed between the bottom 153 and the power storage stack 110. The cooler 190 cools the plurality of unit cells 120. Each of the plurality of spacers 130 is positioned in the second direction DR2 by contacting the cooler 190.

The cooler 190 may be constituted by a cooling pipe through which a liquid or gaseous refrigerant flows, for example.

Here, an example of a method of forming the power storage stack 110 in the housing case 140 in the power storage device 100 according to embodiment 1 will be described.

Fig. 4 is a cross-sectional view showing a state in which a plurality of cells and a plurality of spacers are arranged in the housing case with one cell removed in embodiment 1. Fig. 4 is a cross-sectional view similar to fig. 3, and upper case 160 is omitted for convenience. By housing the last unit cell 120 in the housing case 140 shown in fig. 4, a restraining force acts on the power storage stack 110 in the first direction DR1, and the power storage stack 110 in the present embodiment shown in fig. 3 is formed.

As shown in fig. 4, first, a plurality of unit cells 120 and a plurality of spacers 130 are arranged in a housing case 140. However, one of the plurality of predetermined unit cells 120 disposed in the housing case 140 is excluded from the plurality of unit cells 120 disposed at this time.

As shown in fig. 4, by removing one of the plurality of unit cells 120, two of the plurality of spacers 130 are adjacent to each other in the first direction DR1 without passing through the unit cell 120. Hereinafter, a case will be described in which the remaining unit cells 120 are disposed between the two spacers 130 adjacent to each other, but the remaining unit cells 120 may be disposed at positions in contact with the storage case 140 in the first direction DR 1. In other words, the remaining unit cells 120 may be the unit cells 120 constituting the first end surface 111 or the second end surface 112 of the power storage stack 110.

Fig. 5 is a cross-sectional view showing a state in which a plurality of unit cells and a plurality of spacers are arranged in a housing case excluding one unit cell, and the remaining unit cells are press-fitted in order to form a battery stack in embodiment 1. Fig. 5 is a cross-sectional view similar to fig. 3.

As shown in fig. 5, the remaining unit cells 120 are disposed between two spacers 130 adjacent to each other in the storage case 140. The remaining unit cells 120 are arranged from the other (upper) side in the second direction DR 2. Thereby, the first tapered surface 121 of the remaining unit cells 120 abuts against the first support surface 131 of one of the spacers 130. The second tapered surface 122 of the remaining unit cell 120 abuts against the second support surface 132 of the other spacer 130.

At this time, the remaining unit cells 120 protrude toward the other side (upper side) in the second direction DR2 than the other unit cells 120. While the plurality of cells 120 and the plurality of spacers 130 in embodiment 1 receive the restraining load in the state where all the cells 120 are arranged, the plurality of cells 120 and the plurality of spacers 130 shown in fig. 5 are in a state where the load in the first direction DR1 is very small. The description of the unit cells 120 and the plurality of spacers 130 in the no-load state will be described later.

Then, when the remaining unit cells 120 protruding as described above are pressed into the above-described one (lower) of the second directions DR2, the force Fp of pressing the unit cells 120 into the above-described directions is converted into the pressing force Fq1 and the pressing force Fq2 due to the wedge effect of the unit cells 120 having the first tapered surfaces 121 and the second tapered surfaces 122. The pressing force Fq1 is a force with which the pressed-in unit cell 120 presses the first support surface 131 of the spacer 130 in contact with the first tapered surface 121 thereof. The pressing force Fq2 is a force with which the pressed-in unit cell 120 presses the second support surface 132 of the spacer 130 in contact with the second taper surface 122 thereof.

Due to the component Fr1 of the pressing force Fq1 in the first direction DR1, the spacers 130 and the other unit cells 120 located on the first tapered surface 121 side of the pressed unit cells 120 are compressed in the first direction DR1 by receiving a reaction force from the first inner surface 151 (first inclined portion 151a) of the storage case 140. Due to the component Fr2 of the pressing force Fq2 in the first direction DR1, the spacer 130 and the other unit cells 120 located on the second taper surface 122 side of the pressed unit cell 120 receive a reaction force from the second inner surface 152 (second inclined portion 152a) of the storage case 140, and are compressed in the first direction DR 1. The reaction force from the spacer 130 caused by the components Fr1 and Fr2 in the first direction DR1 causes the pressed-in unit cells 120 to be compressed also in the first direction DR 1.

As described above, in the receiving case 140, the unit cells 120 and the spacers 130 are compressed in the first direction DR1 while the protruding unit cells 120 are inserted between the spacers 130. Thus, the power storage stack 110 according to embodiment 1 is formed in the housing case 140 in a state of receiving the restraining load in the first direction DR 1.

In addition, although the above description has been made of the case where the electricity storage stack 110 is formed by press-fitting the remaining cells 120 between the two spacers 130, the electricity storage stack 110 in embodiment 1 can be formed in the housing case 140 in a state where the restraining load is received in the first direction DR1, similarly to the above case, even in the case where the electricity storage stack 110 is formed by press-fitting the cells 120 that constitute the first end surface 111 or the second end surface 112 of the electricity storage stack 110.

Specifically, when the cell 120 constituting the first end surface 111 of the power storage stack 110 is press-fitted, the first tapered surface 121 of the press-fitted cell 120 is in contact with the first inner side surface 151 (first inclined portion 151a), but the power storage stack 110 can be formed in a state of receiving the restraining load in the first direction DR1 due to the wedge effect similar to that described above. When the unit cell 120 constituting the second end surface 112 of the power storage stack 110 is press-fitted, the second taper surface 122 of the press-fitted unit cell 120 is in contact with the second inner side surface 152 (second inclined portion 152a), but due to the wedge effect similar to that described above, the power storage stack 110 can be formed in a state in which the restraining load is received in the first direction DR 1.

The power storage stack 110 is compressed in the first direction DR1 and receives the restraining load Ft1 in the first direction DR1, but its position is restricted within the housing case 140.

Fig. 6 is a schematic cross-sectional view showing forces acting on the unit cells in the power storage device according to embodiment 1. Fig. 7 is a schematic cross-sectional view showing a no-load state of the battery stack in embodiment 1. In fig. 6 and 7, the power storage device 100 and the power storage stack 110 are illustrated in the same sectional views as in fig. 3, respectively. For ease of explanation, fig. 6 and 7 schematically illustrate the members adjacent to each other in the first direction DR1 while being separated from each other.

As shown in fig. 6, when the length in the first direction DR1 of the power storage stack 110 in the power storage device 100 according to embodiment 1 is Du as viewed from the other side (upper side) in the second direction DR2, and when the length in the first direction DR1 of the power storage stack 110 in the unloaded state as viewed from the other side (upper side) in the second direction DR2 is Ds1 as shown in fig. 7, Ds1> Du. Therefore, the restraining load Ft1 in the first direction DR1 of the accumulator stack 110 can be expressed as Ft1 ≈ K · (Ds 1-Du). Here, K is a spring constant in the first direction DR1 of the power storage stack 110, and hereinafter, the spring constant K of the power storage stack 110 is always regarded as constant for the sake of easy description.

In the present embodiment, the power storage stack 110 may be formed by press-fitting one cell 120 as described above, but the restraining load Ft1 may be controlled by adjusting the force Fp of press-fitting the cell 120 shown in fig. 5.

Specifically, as shown in fig. 5 and 6, the magnitude of the component Fr1(Fr2) in the first direction DR1 of the pressing force Fq1(Fq2) that presses the spacer 130 adjacent to the unit cell 120 by the force Fp of pressing into the unit cell 120 may be directly regarded as the magnitude of the restraining load Ft 1. When the magnitude of the restraining load Ft1 is adjusted to be small, the cell 120 that has been pushed in last may be located on the other (upper) side of the end portion of the adjacent spacer 130 in the second direction DR2 on the one (lower) side. That is, the unit cells 120 that are finally pressed in may be separated from the cooler 190. In this case, a heat conductive agent may be injected in advance between the last pressed unit cell 120 and the cooler 190. Therefore, in power storage device 100 according to embodiment 1, the heat conductive agent may be located between at least one unit cell 120 of the plurality of unit cells 120 and cooler 190.

Next, the force acting on the unit cell 120 in embodiment 1 will be described. As shown in fig. 6, a reaction force in the direction of the first direction DR1 is generated in each of the plurality of unit cells 120 due to the restraining load Ft 1. For example, a reaction force F1 is generated on the first taper surface 121 due to the restraining load Ft1 from the spacers 130 adjacent on the first taper surface 121 side of the unit cells 120. Since the first tapered surface 121 and the first supporting surface 131 of the spacer 130 in contact therewith are not parallel to the second direction DR2, the reaction force F1 is decomposed into a component force F2 in the direction perpendicular to the first tapered surface 121 (first supporting surface 131) and a component force F3 in the direction along the first tapered surface 121 (first supporting surface 131). Since the spacer 130 is made of thermoplastic resin, the frictional force F4 directed to the opposite side of the direction of the component force F3 is generated in the first tapered surface 121 by the component force F3. The magnitude of the frictional force F4 is equal to the magnitude of the force component F3. The same frictional force is also generated on the second taper surfaces 122 of the unit cells 120. Thus, even if the battery stack 110 is subjected to the restraining load Ft1, the plurality of unit cells 120 are restrained in position by their frictional forces. Therefore, in power storage device 100 according to embodiment 1, even if the plurality of battery cells 120 are not fixedly coupled to each other by a member such as a restraining band, the plurality of battery cells 120 are maintained in a state in which the restraining load Ft1 is received and the positions thereof are restricted.

In addition, the unit cells 120 receive a vertical resistance force having the same magnitude as the force component F2 from the first supporting surface 131 of the spacer 130 due to the force component F2. Therefore, when the static friction coefficient between the first tapered surface 121 of the cell 120 and the first supporting surface 131 of the spacer 130 is μ, the maximum static friction force between the first tapered surface 121 and the first supporting surface 131 is μ · F2. The power storage device 100 according to embodiment 1 is configured to be F4< μ · F2.

Next, power storage device 100 according to embodiment 1 will be described in a case where any one of plurality of unit cells 120 generates heat abnormally. As shown in fig. 6, when the unit cell 120 abnormally generates heat, the first support surface 131 of the spacer 130, which is in contact with the first tapered surface 121 of the unit cell 120, is heated. Thereby, the first support surface 131 of the spacer 130 made of thermoplastic resin is thermally deformed, and the static friction coefficient μ between the first tapered surface 121 of the unit cell 120 and the first support surface 131 of the spacer 130 is reduced. As the static friction coefficient μ decreases, the maximum static friction force (μ · F2) between the first tapered surface 121 and the first supporting surface 131 also decreases.

When the maximum static friction force (μ · F2) is reduced to a relationship of μ · F2< F3, the friction force F4 becomes equal to the maximum static friction force (μ · F2), and the component force F3 becomes larger than the friction force F4 which becomes the maximum static friction force. Thereby, the unit cell 120 moves in the direction of the component force F3. That is, the first taper surfaces 121 contact the first support surfaces 131 while the unit cells 120 slide along the first support surfaces 131. Similarly, the second support surface 132 is thermally deformed to reduce the maximum static friction force of the spacer 130 in contact with the second tapered surface 122 of the abnormally heated unit cell 120, and the unit cell 120 slides along the second support surface 132 while the second tapered surface 122 is in contact with the second support surface 132 on the second tapered surface 122 side, similarly to the first tapered surface 121 side.

As described above, when abnormal heat generation occurs in one of the plurality of unit cells 120 in the power storage stack 110, the unit cell 120 is displaced in the other direction (upward) of the second direction DR 2.

Fig. 8 is a schematic cross-sectional view of the power storage device in embodiment 1 showing a state in which the abnormally heated unit cells are displaced. Fig. 9 is a cross-sectional view schematically showing the power storage stack in embodiment 1 in a state where the power storage stack is in an unloaded state in the first direction while maintaining the displacement of the abnormally heated unit cell in the second direction. In fig. 8 and 9, the power storage device 100 and the power storage stack 110 are illustrated in the same sectional views as in fig. 3, respectively. For ease of explanation, fig. 8 and 9 schematically illustrate the members adjacent to each other in the first direction DR1 while being separated from each other.

As shown in fig. 8, the first tapered surface 121 and the second tapered surface 122 of the cell 120 are inclined such that the distance therebetween decreases toward one (lower) of the second directions DR2, and therefore, when the abnormally heated cell 120 is displaced toward the other (upper) of the second directions DR2, as shown in fig. 9, the length Ds2 of the battery stack 110 in the first direction DR1 when viewed from the other (upper) side of the second directions DR2 is made smaller than the length Ds1 in the unloaded state when the cell 120 is not abnormally heated as shown in fig. 7 (Ds2< Ds1) while the abnormally heated cell 120 is kept protruding in the second direction DR2 and the load on the first direction DR1 is made to be in the unloaded state.

As shown in fig. 8 and 9, the restraining load Ft2 in the first direction DR1 in the battery stack 110 in a state in which the abnormally heated unit cell 120 is displaced can be expressed as Ft2 ≈ K · (Ds 2-Du). Here, as described above, since Ds2 is smaller than Ds1, K. (Ds2-Du) < K. (Ds1-Du), i.e., Ft2< Ft 1. As a result, the unit cells 120 are displaced as described above, and the restraining load in the first direction DR1 of the battery stack 110 is reduced. As the restraining load becomes smaller, the thermal conductivity in the first direction DR1 in the battery stack 110 decreases. Therefore, heat conduction from the unit cell 120 that generates heat to the other unit cells 120 can be suppressed.

As described above, in the power storage device 100 according to the first embodiment, in each of the plurality of spacers 130, the first support surface 131 is inclined corresponding to the first tapered surface 121 of the cell 120 adjacent to one side in the first direction DR1 and is in contact with the first tapered surface 121. In each of the plurality of spacers 130, the second supporting surface 132 is inclined corresponding to the second taper surface 122 of the unit cell 120 adjacent to the other side in the first direction DR1 and contacts the second taper surface 122. Each of the plurality of spacers 130 is composed of a thermoplastic resin.

Thereby, a frictional force is generated between the tapered surface of the unit cell 120 and at least one of the first support surface 131 and the second support surface 132 of the spacer 130 made of the thermoplastic resin. Thereby, displacement of the unit cells 120 in the second direction DR2 is suppressed due to the restraining force acting on the power storage stack 110 in the first direction DR 1. Further, the power storage stack 110 can maintain a state of receiving the restraining force. Further, when any one of the plurality of unit cells 120 abnormally generates heat, at least one of the first support surface 131 and the second support surface of the spacer 130 made of thermoplastic resin adjacent to the unit cell 120 that generates heat is thermally deformed. Thereby, the friction coefficient μ between the first support surface 131 (second support surface 132) of the spacer 130 and the first tapered surface 121 (second tapered surface 122) of the unit cell 120 becomes small. As a result, the heat-generating cells 120 are displaced in the second direction DR2 while sliding on the first support surfaces 131 (second support surfaces 132) of the spacers 130, receiving the restraining force. The binding force is reduced by the displacement of the heat-generating unit cells 120. Since the binding force is reduced, heat conduction from the cell 120 that abnormally generates heat in the power storage stack 110 to the other cells 120 can be suppressed.

In power storage device 100 according to embodiment 1, first inclined portion 151a is inclined in correspondence with first tapered surface 121. The second inner side surface 152 includes a second inclined portion 152 a. The second inclined portion 152a is inclined correspondingly to the second tapered surface 122. The power storage stack 110 is held by the housing case 140 in a state where the first end surface 111 is in contact with the first inclined portion 151a and the second end surface 112 is in contact with the second inclined portion 152 a. Thus, the battery stack 110 can be held in the housing case 140 without providing another member such as an end plate between the first end surface 111 and the first inner surface 151 and between the second end surface 112 and the second inner surface 152.

In power storage device 100 according to embodiment 1, each of the plurality of spacers 130 is positioned in second direction DR2 by being in contact with cooler 190. Thereby, the position of the entire electrical storage stack 110 in the second direction DR2 is stabilized. Further, the reliability of power storage device 100 is improved.

(embodiment mode 2)

The following describes the power storage device according to embodiment 2. The power storage device according to embodiment 2 is mainly different from embodiment 1 in a method of positioning a plurality of spacers in a second direction. Therefore, the description of the same structure as that of embodiment 1 is omitted.

Fig. 10 is a schematic cross-sectional view of a power storage device according to embodiment 2. Fig. 10 is a cross-sectional view similar to fig. 3. In fig. 10, the members adjacent to each other in the first direction DR1 are also schematically illustrated as being separated from each other.

As shown in fig. 10, in the power storage device 200 according to embodiment 2, no cooler is provided between the power storage stack 110 and the bottom portion 153.

Therefore, in the power storage device 200 according to embodiment 2, each of the plurality of spacers 230 is positioned in the second direction DR2 by being in contact with the bottom 153. Thus, in the present embodiment, the plurality of spacers 130 are also positioned in the second direction DR2, thereby stabilizing the position of the entire power storage stack 110 in the second direction DR 2. Further, the reliability of power storage device 100 is improved.

While embodiments of the present disclosure have been described, it should be considered that the embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present disclosure is indicated by the claims, and all changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein.