JP2014102915A - Battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an excellent battery pack having a cooling structure of a square secondary battery while suppressing swelling of a battery can.SOLUTION: In a battery pack 81, a plurality of square batteries 1 in each of which a flat type wound electrode group 31 is housed with a winding axis direction X of the flat type wound electrode group extending in a cell width direction Cw of a battery can 11 are juxtaposed, spacers 101 are interposed between battery cans 11 adjacent to each other, and passages of a cooling medium are thereby formed between the battery cans 11. The plurality of spacers 101 are disposed with prescribed intervals kept in a cell height direction Ch of the battery can 11, and each of the spacers has a waveform in which a first inclined part shifting toward the upper side of the cell height direction Ch of the battery can 11 as it shifts from one side of the cell width direction Cw to the other side thereof, and a second inclined part shifting toward the lower side of the cell height direction Ch are alternately and continuously formed in the cell width direction Cw.

Description

  The present invention relates to a battery pack in which prismatic secondary batteries are stacked with spacers interposed between a plurality of prismatic secondary batteries.

  Conventionally, in the field of rechargeable secondary batteries, aqueous batteries such as lead batteries, nickel-cadmium batteries, and nickel-hydrogen batteries have been mainstream. However, as electric devices have become smaller and lighter, lithium-ion secondary batteries having a high energy density have attracted attention, and their research, development, and commercialization have been promoted rapidly.

  On the other hand, electric vehicles (EV) and hybrid electric vehicles (HEV) that assist part of driving with electric motors have been developed by each automobile manufacturer due to global warming and depleted fuel problems. Secondary batteries have been demanded. As a power source that meets such requirements, a non-aqueous lithium ion secondary battery having a high voltage has attracted attention. In particular, prismatic lithium ion secondary batteries have excellent volumetric efficiency when packed into packs, and therefore, there are increasing expectations for development for HEVs or EVs.

  However, in large current applications such as HEV or EV, heat generation of the battery is inevitable, and cooling of the battery is necessary. Generally, cooling is performed by providing a gap between each battery of an assembled battery configured by electrically connecting a plurality of batteries in series and / or in parallel, and flowing a cooling medium such as air through the gap. Yes. On the other hand, inside the battery, the electrode material accommodated in the battery can expands with charging and discharging, and the battery can also expands due to the influence thereof.

  As a means for cooling the battery while suppressing the expansion of the battery can, a technique has been proposed in which spacers having a plurality of slit portions through which a cooling medium passes are arranged between the batteries (Patent Document 1).

  In Patent Document 2, a flow path through which cooling air flows is formed by a space sandwiched between ribs, and the ribs of the battery holder are formed so that the height in the vertical direction gradually decreases along the flow of cooling air. The technique to do is proposed (patent document 2).

JP 2006-48996 JP 2008-159439 A

  In the structure disclosed in Patent Document 1, the spacer is arranged in parallel with the opening of the battery container. In a prismatic lithium ion secondary battery for HEV or EV, the flat wound group is accommodated in the battery container in a state where the winding axis direction of the flat wound group and the opening of the battery container are parallel to each other. Therefore, the spacer is arranged in parallel with the winding axis direction of the flat wound group.

  On the other hand, the pressing force acting on the battery container due to the expansion accompanying the charging / discharging of the flat wound group is distributed in the direction perpendicular to the winding axis direction. Therefore, when the spacer is arranged in parallel to the winding axis, it is not efficient for suppressing the expansion of the battery can.

  Further, in the structure disclosed in Patent Document 2, since the rib is inclined so as to move downward as it moves from one side to the other side in the cell width direction of the battery cell, the cell height direction upper side In the lower region, a region of a dead end where cooling air does not flow is formed. Therefore, the cooling air cannot flow over the entire side surface of the battery cell, and the cooling efficiency may deteriorate.

  In view of the above-described case, an object of the present invention is to provide an excellent assembled battery having a cooling structure for a square secondary battery while suppressing expansion of a battery can.

  In order to solve the above-mentioned problem, the present invention provides a flat wound electrode group in which the winding axis direction of the flat wound electrode group extends along the cell width direction of the battery can. A plurality of rectangular secondary batteries housed in the battery can are arranged in the cell thickness direction of the battery can, a spacer is interposed between the battery cans adjacent to each other, and a cooling medium is provided along the cell width direction of the battery can. The battery pack is formed with a flow path to be flowed, wherein a plurality of the spacers are arranged at predetermined intervals in the cell height direction of the battery can and from one side to the other side in the cell width direction. A first inclined portion that moves toward the upper side in the cell height direction of the battery can as it moves, and a lower side in the cell height direction of the battery can as it moves from one side to the other side in the cell width direction The second inclined portion that moves toward the battery is the battery. It is characterized by having a cell width direction are formed alternately and continuously waveform shape.

  ADVANTAGE OF THE INVENTION According to this invention, the outstanding assembled battery which has the cooling structure of the square secondary battery can be provided, suppressing the expansion | swelling of a battery can effectively. Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

Schematic of an electrode. The external appearance perspective view of the state which developed a part of flat type winding electrode group. The disassembled perspective view of a square secondary battery. The perspective view of a square secondary battery. The image figure for demonstrating the deformation | transformation state of a battery container by expansion | swelling of a flat wound electrode group. The schematic diagram explaining the structure of the assembled battery concerning 1st Embodiment. The figure which looked at the separator and the square secondary battery from the A direction of FIG. The figure explaining 2nd Embodiment. The figure which shows the other structural example of a separator. The figure which shows the other structural example of a separator. The perspective view which shows one Example of the assembled battery concerning this embodiment. The perspective view which shows the assembly state of a square battery and an intermediate holder. The perspective view which shows the decomposition | disassembly state of FIG.

  Embodiments in which the present invention is applied to an assembled battery of a prismatic lithium ion secondary battery will be described below with reference to the drawings.

  First, the configuration of a prismatic secondary battery that is commonly used in both the first embodiment and the second embodiment will be described.

  1 is a schematic view of an electrode, FIG. 2 is a perspective view of a flat wound electrode group, FIG. 3 is an exploded perspective view of a prismatic secondary battery, and FIG. 4 is a perspective view of the prismatic secondary battery.

  The prismatic secondary battery 1 is a prismatic lithium ion secondary battery (unit cell) for HEV or EV, and has a configuration in which a power generation element 3 is accommodated in a flat box-shaped battery container 2 as shown in FIG. Have. The battery container 2 includes a battery can 11 having an opening 11 a and a battery lid 21 that seals the opening 11 a of the battery can 11. As shown in FIGS. 1 and 2, the power generating element 3 includes a flat wound electrode group 31 wound in a flat shape in a state where separators 33 and 35 are interposed between a positive electrode 34 and a negative electrode 32. have.

  The battery can 11 and the battery lid 21 are both made of an aluminum alloy, and the battery lid 21 is welded to the battery can 11 by laser welding. As shown in FIG. 3, the battery can 11 has a pair of wide side surfaces PW, a pair of narrow side surfaces PN, and a bottom surface PB. The battery lid 21 is provided with a positive electrode terminal 51 and a negative electrode terminal 61 (a pair of electrode terminals) via an insulating member, and constitutes a lid assembly. In addition to the positive electrode terminal 51 and the negative electrode terminal 61, the battery lid 21 has a gas discharge valve 71 that opens when the pressure in the battery container 2 rises above a predetermined value and discharges the gas in the battery container 2, A liquid injection port 72 for injecting an electrolytic solution into the battery container 2 is disposed.

  The positive electrode terminal 51 and the negative electrode terminal 61 are disposed at positions separated from each other on one side and the other side in the longitudinal direction of the battery lid 21. The positive terminal 51 and the negative terminal 61 include external terminals 52 and 62 disposed outside the battery cover 21 and connection terminals 53 and 63 that penetrate the battery cover 21 and have one end electrically connected to the external terminals 52 and 62. Have. The positive external terminal 52 and the connection terminal 53 are made of an aluminum alloy, and the negative external terminal 62 and the connection terminal 63 are made of a copper alloy. Bolts 52a and 62a for fastening the bus bar protrude from the external terminals 52 and 62.

  Insulating members (not shown) are interposed between the connection terminals 53 and 63 and the external terminals 52 and 62, respectively, and are electrically insulated from the battery lid 21. The other ends of the connection terminals 53 and 63 are conductively connected to the current collecting terminals 54 and 64 inside the battery lid 21. The current collecting terminals 54 and 64 extend from the inside of the battery lid 21 toward the bottom surface PB of the battery can 11 and are conductively connected to the flat wound electrode group 31. The flat wound electrode group 31 is disposed and supported between the current collecting terminal 54 of the positive electrode terminal 51 and the current collecting terminal 64 of the negative electrode terminal 61, and is supported by the lid assembly and the flat wound electrode group 31. The power generation element assembly is configured.

  As shown in FIGS. 1 and 2, the flat wound electrode group 31 is obtained by winding a strip-like laminate in which the negative electrode 32, the positive electrode 34, and the separators 33 and 35 are laminated in order into a flat shape. It is configured. The flat wound electrode group 31 includes a pair of flat surfaces 31P extending in parallel with each other along the winding direction (Y direction in FIG. 2), and between each one end of the pair of flat surfaces 31P and each It has a pair of curved surfaces 31T formed continuously between the other end portions, and its cross-sectional shape is an oval shape connecting two semicircles with a straight line.

  As shown in FIG. 3, the flat wound electrode group 31 is inserted into the battery can 11 from one curved surface 31T side. In the battery can 11, the pair of flat surfaces 31 </ b> P are opposed to the pair of wide side surfaces PW, the one curved surface 31 </ b> T is opposed to the bottom surface PB, and the other curved surface 31 </ b> T is opposed to the battery lid 21. Retained.

  The negative electrode 32 includes a negative electrode coating portion 32b in which a negative electrode mixture layer is formed on the front and back surfaces of the negative electrode metal foil, and a negative electrode uncoated negative electrode metal foil with a constant width exposed along the long side direction on one side in the width direction. It has a work part 32a. The positive electrode 34 includes a positive electrode coating portion 34b having a positive electrode mixture layer formed on the front and back surfaces of the positive electrode metal foil, and a positive electrode in which the positive electrode metal foil is exposed with a constant width along the long side direction on the other side in the width direction. It has an uncoated portion 34a.

  The separators 33 and 35 are made of, for example, a polyethylene-made microporous insulating material, and have a role of insulating the positive electrode 34 and the negative electrode 32. The negative electrode coating part 32b of the negative electrode 32 is larger in the width direction than the positive electrode coating part 34b of the positive electrode 34, so that the positive electrode coating part 34b is always sandwiched between the negative electrode coating part 32b.

  The positive electrode uncoated portion 34a and the negative electrode uncoated portion 32a are bundled on the flat surface 31P and connected to the current collecting terminals 54 and 64 connected to the external terminals 52 and 62 by welding or the like. The separators 33 and 35 are wider than the negative electrode coated portion 32b in the width direction, but are bundled because they are wound at positions where the metal foil surface is exposed at the positive electrode uncoated portion 34a and the negative electrode uncoated portion 32a. This will not interfere with welding. As shown in FIG. 2, the positive electrode 34 and the negative electrode 32 are arranged such that the positive electrode uncoated portion 34 a and the negative electrode uncoated portion 32 a are positioned at one side and the other side in the winding axis direction (X direction in the drawing). It is piled up and wound around.

  The positive electrode 34 is prepared by mixing lithium-containing double oxide powder as a positive electrode active material, scaly graphite as a conductive material, and polyvinylidene fluoride (PVDF) as a binder in a weight ratio of 85: 10: 5. A slurry obtained by adding and kneading N-methylpyrrolidone (NMP) as a dispersion solvent was applied to both sides of an aluminum foil (positive electrode metal foil) having a thickness of 20 μm, dried, and then pressed and cut. The positive electrode uncoated portion 34a formed on one side in the longitudinal direction of the aluminum foil was used as the positive electrode lead.

  In the negative electrode 32, amorphous carbon powder as a negative electrode active material, PVDF as a binder is added, NMP as a dispersion solvent is added thereto, and a kneaded slurry is applied to both sides of a rolled copper foil having a thickness of 10 μm. It was made by drying and then pressing and cutting. Note that the negative electrode uncoated portion 32a formed continuously on one side in the longitudinal direction of the rolled copper foil was used as the negative electrode lead.

  In this embodiment, amorphous carbon is exemplified as the negative electrode active material. However, the present invention is not limited to this, and natural graphite capable of inserting and removing lithium ions, various artificial graphite materials, coke, etc. The carbonaceous material or the like may be used, and the particle shape is not particularly limited to a scaly shape, a spherical shape, a fibrous shape, a massive shape, or the like.

  When assembling the prismatic secondary battery 1 described above, first, as shown in FIG. 1, the positive electrode 34 and the negative electrode 32 are sequentially stacked with separators 33 and 35 interposed therebetween so that the two electrodes are not in direct contact with each other. Match. Then, with the one side in the long side direction as the winding center, the flat wound electrode group 31 is fabricated by winding in a flat shape as shown in FIG. During winding, both the positive electrode 34, the negative electrode 32, and the separators 33 and 35 are subjected to meandering control so that the electrode end face and the separator end face are in a fixed position while being applied with a load of 10 N in the electrode length and the separator long side direction. While making. At this time, the positive electrode uncoated portion 34a and the negative electrode uncoated portion 32a were wound in an overlapping manner so as to be positioned on opposite end surfaces of the flat wound electrode group 31.

  Next, the flat wound electrode group 4 is assembled to the lid assembly in which the positive electrode terminal 51 and the like are attached to the battery lid 21 in advance, and the positive electrode uncoated portion 34a serving as the positive electrode lead and the positive electrode The current collecting terminal 54 is joined and electrically conducted by ultrasonic welding, and similarly, the negative electrode uncoated portion 32a that is the negative electrode lead and the negative current collecting terminal 64 are joined by ultrasonic welding and are electrically connected. Conducting to form a power generation element assembly. Then, the battery can 11 and the power generation element assembly are brought close to each other, the flat wound electrode group 31 is inserted into the battery can 11 from the opening 11a of the battery can 11, and the flat wound electrode group 31 is attached. Accommodate. An insulating resin sheet (not shown) is interposed between the battery can 11 and the flat wound electrode group 31. And the opening part 11a of the battery can 11 is obstruct | occluded with the battery cover 21, and between the battery can 11 and the battery cover 21 is laser-welded and sealed.

  Next, a predetermined amount of nonaqueous electrolyte that can infiltrate the entire flat wound electrode group 31 is injected into the battery container 2 from the injection port 72 of the battery lid 21, and then plugged into the injection port 72. 73 is attached and closed, and the plug 73 is laser welded to the battery lid 21 and sealed. Thereby, the square secondary battery 1 is in a completed state as shown in FIG.

In the non-aqueous electrolyte, lithium hexafluorophosphate (LiPF ₆ ) is dissolved at a concentration of 1 mol / liter in a mixed solution in which ethylene carbonate and dimethyl carbonate are mixed at a volume ratio of 1: 2. Was used.

  In this embodiment, PVDF is exemplified as the binder, but polytetrafluoroethylene (PTFE), polyethylene, polystyrene, polybutadiene, butyl rubber, nitrile rubber, styrene / butadiene rubber, polysulfide rubber, nitrocellulose, cyanoethylcellulose, various types Polymers such as latex, acrylonitrile, vinyl fluoride, vinylidene fluoride, propylene fluoride, chloroprene fluoride, and mixtures thereof may be used.

Furthermore, in the present embodiment, a nonaqueous electrolytic solution in which LiPF ₆ is dissolved in a mixed solution of ethylene carbonate and dimethyl carbonate is illustrated, but nonaqueous electrolysis in which a general lithium salt is used as an electrolyte and this is dissolved in an organic solvent. A liquid may be used, and the present invention is not particularly limited to the lithium salt or organic solvent used. For example, as the electrolyte, LiClO ₄ , LiAsF ₆ , LiBF ₄ , LiB (C ₆ H ₅ ) ₄ , CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, or a mixture thereof can be used. Examples of the organic solvent include propylene carbonate, ethylene carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, tetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, Diethyl ether, sulfolane, methyl sulfolane, acetonitrile, propiontonyl, etc., or a mixed solvent of two or more of these may be used, and the mixing ratio is not limited.

  FIG. 5 is an image diagram for explaining a deformed state of the battery case due to expansion of the flat wound electrode group. In FIG. 5, the deformation state is shown extremely in order to easily understand the deformation state of the battery case, and actually, for example, the deformation amount is a slight deformation amount that is difficult to confirm with the naked eye. .

  As shown in FIG. 5, the flat wound electrode group 31 of the prismatic secondary battery 1 expands with charge and discharge when the wide side surface of the battery can 11 is not constrained. Then, four boundary portions 31L formed at the boundary between the flat surface 31P and the curved surface 31T of the flat wound electrode group 31 move outward along the cell thickness direction Cd, and the battery The wide side surface PW of the can 11 is pressed from the inside.

  The battery can 11 is pressed with the strongest pressing force F1 at the boundary facing portion 12 that faces the boundary portion 31L in the wide side surface PW. And as it goes to the inner side of the flat wound electrode group 31 from the boundary portion 31L, the pressing forces F2 and F3 become smaller and become minimum at the center position in the winding direction of the flat wound electrode group 31.

  Thus, the pressing force (expansion force) acting on the battery can 11 due to the expansion of the flat wound electrode group 31 is the cell height direction which is a direction perpendicular to the winding axis direction of the flat wound electrode group 31. It is distributed along Ch and differs depending on the position in the cell height direction Ch. In the figure, the lengths of the arrows F1 to F3 indicate the magnitude of the pressing force.

  On the other hand, in the cell width direction Cw (depth direction in FIG. 5) parallel to the winding axis direction of the flat wound electrode group 31, the pressing force acting on the battery can 11 is constant regardless of the position. Yes. That is, the expansion force accompanying charging / discharging of the flat wound electrode group 31 has a weak interaction in the cell height direction Ch perpendicular to the winding axis direction, and is mutually in the cell width direction Cw parallel to the winding axis direction. The action is working strongly. That is, when a force for suppressing the expansion of the flat wound electrode group 31 is applied at an arbitrary point on the wide side surface PW, the force has a small influence on the cell height direction Ch perpendicular to the winding axis direction. However, the influence on the cell width direction Cw parallel to the winding axis direction increases.

<First Embodiment>
A first embodiment will be described with reference to FIGS. 6 and 7.
FIG. 6 is a schematic diagram illustrating the configuration of the assembled battery according to the first embodiment, and FIG. 7 is a view of the separator and the square secondary battery as viewed from the direction A in FIG.

  The assembled battery 81 includes six prismatic secondary batteries 1 arranged in parallel with a certain gap therebetween and electrically connected in series by a bus bar 82. A spacer 101 is disposed between the adjacent square secondary batteries 1. In the assembled battery 81, a pair of metal plates such as stainless steel and copper (not shown) are arranged on both sides of the assembled battery 81 in the arrangement direction, and restrained by bolts or the like, thereby restraining the expansion of each rectangular secondary battery 1. ing.

  The spacer 101 is interposed between the wide side surfaces PW of the adjacent prismatic secondary batteries 1 facing each other, and is disposed on the flat surface 31P of the flat wound electrode group 31 with the wide side surface PW of the battery can 11 interposed therebetween. It is arranged at the opposite position.

  The spacer 101 can be made of a resin material such as glass epoxy resin, polypropylene, or polybutylene terephthalate resin, or a metal material such as aluminum, copper, or stainless steel. Although not shown, the spacer 101 may be integrated with a container that houses the assembled battery 81.

  The spacer 101 is configured by continuous repetition of two types of inclined portions 101a and 101b having different predetermined stretching angles with respect to the cell width direction Cw that is the winding axis direction of the flat wound electrode group 31; A plurality of cells are arranged at predetermined intervals in the cell height direction Ch, which is a direction perpendicular to the winding axis direction.

  As shown in FIG. 7, a plurality of spacers 101 are arranged at predetermined intervals in the cell height direction Ch of the battery can 11. Each spacer 101 includes a first inclined portion 101a that moves toward the upper side in the cell height direction Ch of the battery can 11 as it moves from one side to the other side in the cell width direction Cw, and one of the cell width directions Cw. The second inclined portions 101b that move downward in the cell height direction Ch of the battery can 11 as the transition from the side toward the other side are alternately and continuously formed in the cell width direction Cw of the battery can 11. Has a corrugated shape.

  The spacer 101 extends in parallel along the wide side surface PW of the battery can 11 and is continuously provided from one end portion to the other end portion of the battery can 11 in the cell width direction Cw. Each of the first inclined portion 101a and the second inclined portion 101b has a linear shape, and is set so that an angle between the first inclined portion 101a and the second inclined portion 101b is 10 ° or more and less than 90 °.

  The spacer 101 has a corner portion 101c between the first inclined portion 101a and the second inclined portion 101b. The corner portion 101c connects the first inclined portion 101a and the second inclined portion 101b to each other, and the entire spacer 101 has a shape that forms a triangular wave shape.

  The pressing force acting on the battery can 11 by the expansion of the flat wound electrode group 31 is distributed in the cell height direction Ch, which is a direction perpendicular to the winding axis direction, as shown in FIG. However, the size is constant in the cell width direction Cw, which is parallel to the winding axis direction (depth direction in FIG. 7).

  The expansion force associated with charging / discharging of the flat wound electrode group 31 has a weak interaction in a direction perpendicular to the winding axis direction and a strong interaction in a direction parallel to the winding axis direction. When a force that suppresses the expansion of the winding group at any one point of the wide side surface PW is applied, the force has a small influence on the direction perpendicular to the winding axis direction, but the direction parallel to the winding axis direction The influence on is increased.

  Since the spacer 101 includes the first inclined portion 101a and the second inclined portion 101b extending at a predetermined inclination angle with respect to the cell width direction Cw, the battery 101 is arranged along the direction in which the pressing force is distributed. The wide side surface of the can 11 can be pressed. Therefore, the force which suppresses the expansion of the flat wound electrode group 31 can be strengthened, and the deformation of the battery can 11 is effective as compared with the spacer having a structure extending in parallel along the conventional cell width direction Cw. Can be suppressed.

  Since the spacer 101 has a strong force for suppressing the expansion of the flat wound electrode group 31, the arrangement interval between the spacers 101 can be expanded as compared with the conventional spacer, and the cooling formed along the wide side surface PW. A larger passage area of the medium passage can be secured.

  Further, the spacer 101 is provided continuously over the cell width direction Cw of the battery can 11, and the end of the spacer 101 is disposed at the end face position of the battery can 11 in the cell width direction Cw. Therefore, a continuous flow path can be formed from one side to the other side of the cell width direction Cw of the battery can 11. Therefore, the portion of the narrow path as in Patent Document 2 is not formed, and the cooling medium AF can be circulated along the entire surface of the wide side surface PW of the battery can 11 so that the cooling is efficiently performed. .

<Second Embodiment>
A second embodiment will be described with reference to FIG.
FIG. 8 is a diagram for explaining the second embodiment and corresponds to FIG. 6.

  In the first embodiment, the configuration in which the intersections of the first inclined portion 101a and the second inclined portion 101b are connected to each other by the corner portion 101c has been described. However, in this embodiment, the curved portion is used instead of the corner portion 101c. The parts 101d are connected to each other.

  As shown in FIG. 9, the spacer 101 has a curved portion 101d between the first inclined portion 101a and the second inclined portion 101b. The curved portion 101d has an arc shape that smoothly connects the first inclined portion 101a and the second inclined portion 101b. In this way, by connecting the first inclined portion 101a and the second inclined portion 101b with the curved portion 101d, it is possible to reduce pressure loss when a cooling medium such as air passes between the spacers. .

  The present invention is not limited to the contents of the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

  For example, in the first and second embodiments described above, the first inclined portion 101a and the second inclined portion 101b of the spacer 101 are connected without a break from one end to the other end in the cell width direction Cw. Although the configuration has been described, a notch 101e may be provided in the middle.

  FIG. 9 and FIG. 10 are diagrams showing another configuration example of the separator in each of the above-described embodiments, and correspond to FIG.

  As shown in FIGS. 9 and 10, each spacer 101 has a central position in the cell width direction Cw and a space between the first inclined portion 101 a and the second inclined portion 101 b in the cell height direction Ch of the battery can 11. It has a notch 101e that is notched. The notch 101e allows a plurality of flow paths formed between the spacers 101 to communicate with each other in the middle of the flow paths. The notch 101e can prevent foreign matters such as dust from accumulating in the flow path.

  In each of the above embodiments, the first inclined portion 101a and the second inclined portion 101b have a linear shape, and the entire spacer 101 has a triangular wave shape. However, the spacer 101 is a so-called spacer. For example, the first inclined portion 101a and the second inclined portion 101b may have a curved shape, and the entire spacer 101 may have a sinusoidal shape.

[Example]
Next, the configuration of a specific example in the first embodiment will be described with reference to FIGS. 11 is a perspective view showing an example of the assembled battery according to the first embodiment, FIG. 12 is a perspective view showing an assembled state of the prismatic secondary battery and the intermediate holder, and FIG. 13 is an exploded view of FIG. FIG.

  The assembled battery 81 includes a plurality of prismatic secondary batteries 1 and a cell holder 91 that holds the prismatic secondary batteries 1 in a stacked state. The cell holder 91 can be made of, for example, a resin material such as glass epoxy resin, polypropylene, or polybutylene terephthalate resin, or a metal material such as aluminum, copper, or stainless steel.

  The cell holders 91 are disposed between the intermediate cell holders 92 interposed between the adjacent square secondary batteries 1 and the intermediate cell holders 92 disposed at both ends in the stacking direction of the plurality of rectangular secondary batteries 1 held by the intermediate cell holders 92. And a pair of end cell holders 93 that hold the prismatic secondary battery 1. The end cell holder 93 has a structure in which the intermediate cell holder 92 is divided at the center position in the stacking direction. Therefore, in the following description, only the configuration of the intermediate cell holder 92 will be described, and the detailed description of the configuration of the end cell holder 93 will be omitted by attaching the same reference numerals as the configuration of the intermediate cell holder 92.

  For example, as shown in FIG. 12, the intermediate cell holder 92 includes two end spacers 102 and 102 disposed at positions facing the upper and lower ends of the wide side surface PW of the battery can 11, and the upper end of the wide side surface PW. There are four spacers 101 (hereinafter referred to as intermediate spacers 101) arranged at positions facing the region between the first and lower end portions. Each intermediate spacer 101 is disposed at a position facing the flat surface 31P of the flat wound electrode group 31 with the wide side surface PW interposed therebetween.

  Four intermediate spacers 101 are arranged at predetermined intervals in the cell height direction Ch of the battery can 11. In the intermediate spacer 101, first inclined portions 101 a and second inclined portions 101 b having a linear shape are alternately and continuously formed in the cell width direction Cw of the battery can 11. The intermediate spacer 101 extends in parallel along the wide side surface PW of the battery can 11 and is continuously provided from one end to the other end of the battery can 11 in the cell width direction Cw. .

  As shown in FIGS. 12 and 13, the intermediate cell holder 92 has a pair of side walls 111, 111 facing each other at both ends in the cell width direction and extending in the stacking direction, and extending in the stacking direction at the lower end in the cell height direction. And a bottom wall portion 112 that connects the lower end portions of the pair of side wall portions 111 and 111. The pair of side wall portions 111 of the intermediate cell holder 92 are opposed to the narrow side surface PN of each square secondary battery 1 disposed on one side and the other side in the stacking direction, and the bottom wall portion 112 is one side in the stacking direction. And the bottom surface PB of each square secondary battery 1 disposed on the other side. The pair of side wall portions 111 and 111 and the bottom wall portion 112 are connected to the pair of side wall portions 111 and 111 and the bottom wall portion 112 of the intermediate cell holder 92 disposed on one side or the other side in the stacking direction.

  The pair of side wall portions 111, 111 includes a first opening 111a communicating with the space between the end spacers 102, 102 and the intermediate spacer 101, and a plurality of intermediate spacers arranged side by side in the cell height direction. A second opening 111b that communicates with the space between the first and second spaces 101 is formed to be open so that the cooling medium can pass from one side to the other side in the cell width direction Cw of the intermediate cell holder 92. .

  The assembled battery 81 having the above configuration includes the first inclined portion 101a and the second inclined portion 101b that the intermediate spacer 101 extends with a predetermined inclination angle with respect to the cell width direction Cw. The wide side surface PW of the battery can 11 can be pressed along the direction in which the pressure is distributed. Therefore, the force which suppresses the expansion of the flat wound electrode group 31 can be strengthened, and the deformation of the battery can 11 is effective as compared with the spacer having a structure extending in parallel along the conventional cell width direction Cw. Can be suppressed.

  Since the intermediate spacer 101 has a strong force for suppressing the expansion of the flat wound electrode group 31, the arrangement interval between the spacers 101 can be expanded as compared with the conventional spacer. Therefore, for example, the number of intermediate spacers 101 can be reduced to three or two, and a larger passage area of the cooling medium passage formed along the wide side surface PW can be secured.

  The intermediate spacer 101 is continuously provided over the cell width direction Cw of the battery can 11, and the end of the intermediate spacer 101 is disposed at the end face position of the battery can 11 in the cell width direction Cw. . Therefore, a continuous flow path can be formed from one side to the other side of the cell width direction Cw of the battery can 11, and the cooling medium AF can be circulated along the entire wide side surface PW of the battery can 11, High cooling efficiency can be obtained.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the spirit of the present invention described in the claims. It can be changed. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. Furthermore, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

DESCRIPTION OF SYMBOLS 1 Square secondary battery 2 Battery container 3 Power generation element 11 Battery can 12 Boundary facing part 21 Battery cover 31 Flat wound electrode group 31P Plane part 31T Curved part 31L Boundary part 81 Battery assembly 101 Spacer 102 End spacer

Claims (5)

A prismatic secondary battery in which the flat wound electrode group is accommodated in the battery can in a posture state in which the winding axis direction of the flat wound electrode group extends along the cell width direction of the battery can, the battery A battery pack in which a plurality of batteries are arranged in the cell thickness direction of the can and a spacer is interposed between the battery cans adjacent to each other to form a flow path through which a cooling medium flows along the cell width direction of the battery can. And
A plurality of the spacers are arranged at a predetermined interval in the cell height direction of the battery can, and as the cell width direction moves from one side to the other side, on the cell height direction upper side of the battery can. The battery can includes a first inclined portion that moves toward the lower side and a second inclined portion that moves toward the lower side in the cell height direction of the battery can as it moves from one side to the other side in the cell width direction. A battery pack having a wave shape formed alternately and continuously in the cell width direction.   The assembled battery according to claim 1, wherein the spacer is provided continuously across the cell width direction of the battery can.   The assembled battery according to claim 2, wherein the spacer has a corner portion between the first inclined portion and the second inclined portion.   The assembled battery according to claim 2, wherein the spacer has a curved portion between the first inclined portion and the second inclined portion.   The said spacer has a notch part notched over the cell height direction of the said battery can between the said 1st inclination part and the said 2nd inclination part, The Claim 2 to Claim 4 characterized by the above-mentioned. The assembled battery according to any one of the above.

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