POWER STORAGE MODULE

A power storage module includes: at least one cylindrical power storage device; and an upper holder that holds the power storage device in an axial direction. The upper holder includes a container that houses the power storage device and a hole that penetrates the upper holder along an axial direction around the container. A distance between the container and the hole in plan view is smaller than a distance between the container and the adjacent container in plan view or a distance between the container and an edge of the upper holder in plan view.

TECHNICAL FIELD

The present disclosure relates to a power storage module.

BACKGROUND ART

A power storage module is known as a power source including a plurality of power storage devices. When an impact is applied from the outside of the power storage module, a large load acts on the power storage device, the power storage device is largely deformed, and the safety of the power storage module may be impaired.

As a measure against the above problem, for example, in an energy storage module disclosed in PTL 1, a pipe holder is provided between adjacent power storage devices, and when an impact is applied from a side surface of the power storage module, the pipe holder does not move and the power storage device is not deformed.

CITATION LIST

Patent Literature

SUMMARY OF THE INVENTION

Technical Problem

However, in the power storage module disclosed in PTL 1, the number of components is increased by providing the pipe holder.

An object of the present disclosure is to provide an energy storage module capable of suppressing deformation of an power storage device when an impact is applied from a side surface without increasing the number of components.

Solution to Problem

A power storage module according to one aspect of the present disclosure includes: at least one cylindrical power storage device; and a holder that holds one side or an other side of the power storage device along the axis of the power storage device. The holder includes a container that houses one end or an other end of the power storage device and a hole that penetrates the holder along the axis around the container. A distance between the container and the hole in plan view is smaller than a distance between the container and the adjacent container in plan view or a distance between the container and an edge of the holder in plan view.

Advantageous Effect of Invention

According to one aspect of the present disclosure, when an impact is applied from a side surface of the power storage module, a portion between the hole and the container serves as a fracture starting point, and the entire holder is deformed. With such a configuration, an impact of the power storage module can be absorbed by the whole holder and hence, deformation of the power storage device can be suppressed. In other words, according to one aspect of the present disclosure, it is possible to suppress deformation of the power storage device when an impact is applied from the side surface without increasing the number of components. As a result, the safety of the power storage module is not impaired.

DESCRIPTION OF EMBODIMENT

Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. Shapes, materials, and numbers to be described below are examples, and can be appropriately changed according to specifications of a power storage module.

Power storage module5of an exemplary embodiment will be described with reference toFIG.1.FIG.1is a side sectional view illustrating power storage module5. Hereinafter, a side where upper holder10as a holder holds power storage device6with respect to power storage module5and power storage device6will be described as an upper side along the axis of the power storage device.

Power storage module5is mainly used as a power source for power. Power storage module5is used as a power source of an electric device driven by a motor such as an electric car, an electric power tool, an electric power-assisted bicycle, an electric motorcycle, an electric wheelchair, an electric tricycle, or an electric cart. However, the application of power storage module5is not limited, and power storage module5may be used as a power source of various electric devices used indoors and outdoors, such as a cleaner, a wireless device, a lighting device, a digital camera, and a video camera.

InFIG.1, power storage module5includes a plurality of cylindrical power storage devices6, upper holder10as a holder for holding axially upper sides of the plurality of power storage devices6, and lower holder7for holding lower sides of the plurality of power storage devices6.

In this example, a cylindrical lithium ion secondary battery is used as power storage device6, but power storage device6may be a nickel-metal hydride battery, a capacitor or the like. Power storage device6includes, for example, an electrode group in which a strip-shaped positive electrode and a strip-shaped negative electrode are wound in with a strip-shaped separator interposed therebetween, a cylindrical outer covering can containing the electrode group together with an electrolyte solution, a sealing body sealing an opening of the outer covering can in an insulated state, a foil-shaped positive electrode lead electrically connecting a positive electrode and the sealing body, and a negative electrode lead electrically connecting a negative electrode and the outer covering can. An insulating gasket may be disposed between an outer periphery of the sealing body and an inner peripheral surface of the opening of the outer covering can.

An annular groove is formed near the opening of the outer peripheral surface of the outer covering can. The groove is formed as an annular protrusion on the inner peripheral surface of the outer covering can. The gasket and the sealing body are disposed on the annular protrusion in the outer covering can. Further, the opening end of the outer covering can is swaged to fall down toward an inside of the outer covering can in a state where the gasket is disposed on an inner peripheral side. The sealing body is sandwiched by the swaged opening end and the convex portion along the axis of the power storage device through the gasket and thus the opening of the outer covering can is sealed.

Sealing body may be provided with a current interruption mechanism (CID) or an exhaust valve that ruptures when the inside of outer covering can reaches a predetermined pressure or more. In addition, an insulating plate for insulating the electrode group from the outer covering can may be provided between the electrode group and the bottom of the outer covering can or between the electrode group and the protrusion (groove). When the insulating plate is provided, the positive electrode lead may extend through a through-hole formed in the insulating plate. The negative electrode lead may pass through the through-hole formed in the insulating plate or may extend while bypassing the insulating plate.

In an upper part of power storage device6, a positive electrode terminal is formed on a top surface of the sealing body, and a negative electrode terminal is disposed toward an upper end portion (swaged opening end) of the outer covering can. The electrode groups may be connected such that the outer covering can functions as a positive electrode terminal and the sealing body functions as a negative electrode terminal.

A plurality of power storage devices6are densely filled in power storage module5in consideration of safety, and adjacent power storage devices6are arranged substantially close to each other. In power storage device6, for example, in plan view, six power storage devices6are arranged so as to surround one power storage device6(hereinafter, staggered arrangement). The plurality of power storage devices6may be connected in series or in parallel to each other through a conductive current collector (not illustrated) disposed near upper holder10. At this time, the position where the lead extending from the current collector is connected to the power storage device may be the top surface of the sealing body as the positive electrode terminal and the opening end of the swaged outer covering can as the negative electrode terminal. The bottom of the outer covering can positioned on the lower side of the power storage device as the negative electrode terminal may be connected to the lead of the current collector through the opening of lower holder7.

As described above, upper holder10holds the upper side of the plurality of power storage devices6. Upper holder10is made of thermoplastic resin. The thermoplastic resin is roughly classified into general-purpose plastics and engineering plastics, and polyethylene, polypropylene, polyamide, ABS, and the like are used. Details of upper holder10will be described later.

As described above, lower holder7holds the lower sides of the plurality of power storage devices6. Similarly to upper holder10, lower holder7is formed of, for example, thermoplastic resin. Although some exemplary embodiments of upper holder10will be described below, lower holder7may have a similar configuration, and both upper holder10and lower holder7may have a similar configuration. In the power storage module of the present disclosure, an intermediate holder may be provided between upper holder10and lower holder7. The intermediate holder has a container that is a through hole at a position corresponding to the containers of upper holder10and lower holder7. The following configuration of upper holder10can also be applied to an intermediate holder.

Upper holder10as an example of the exemplary embodiment will be described with reference toFIG.2.FIG.2is a cross-sectional view and a partially enlarged view illustrating upper holder10.

Upper holder10has a bottom surface facing lower holder7, and has a plurality of containers11formed on the bottom surface and in which part near upper ends of respective power storage devices6are housed, and holes15formed so as to penetrate the containers11along the axis of the power storage device.

An upper end of power storage device6is fitted to container11. With such a configuration, the upper end of power storage device6is held by upper holder40. Container11includes a ceiling having a bottom surface facing an upper end surface of power storage device6and wall12having an inner peripheral surface facing a side peripheral surface of power storage device6.

Holes15are formed at equal intervals (for example, at 60° intervals) along the periphery of the container11in plan view. In other words, since the containers11(the power storage devices6) are arranged in a staggered manner, the holes15are formed between the three containers11in plan view. hole15is a through hole having a substantially triangular prism shape, and is formed such that each corner15R faces each adjacent container11. Corner15R is formed in an R shape. In addition, hole15A formed along the edge located at the outermost periphery of the bottom surface of upper holder10among the holes15has an opening area smaller than that of the other holes15. Here, “facing the container” means that the edge of the opening forming the hole extends so as to approach container11.

The distance between container11and hole15in plan view is smaller than the distance between container11and adjacent container11in plan view or the distance between container11and the edge of upper holder10in plan view. In other words, in plan view of upper holder10, a portion between corner15R of hole15and container11is the thinnest portion of the region of upper holder20. Note that, in a case where each distance here can take a plurality of values, the distance is a minimum value of the plurality of values.

According to upper holder10, when an impact is applied from the side surface of power storage module5, the region between corner15R of hole15, which is the thinnest in plan view of upper holder10, and container11is broken as a fracture starting point, and the entire upper holder10is deformed. With such a configuration, an impact of power storage module5can be absorbed by upper holder10and hence, deformation of power storage device6can be suppressed. In other words, deformation of power storage device6can be suppressed when an impact is applied from the outside of power storage module5(for example, a side surface of power storage module5) without increasing the number of parts. As a result, the safety of power storage module5is not impaired. In addition, by making hole15A formed at the edge of the bottom surface of upper holder10smaller in opening area than other holes15, rigidity of the periphery of upper holder10can be improved.

Upper holder20as an example of the exemplary embodiment will be described with reference toFIG.3.FIG.3is a cross-sectional view of upper holder20.

In upper holder20, holes25are formed at equal intervals (for example, at 180° intervals in the respective containers constituting the rows at both ends) along the periphery of container21in plan view. In the edge of upper holder20, hole25A is formed at a position where a distance between the edge and container21is minimized. Hole25A is smaller in opening area than other holes25. Configurations (wall22and the like) other than these are similar to those of upper holder10described above, and thus the description thereof is omitted. With such a configuration, the number of holes25and25A surrounding one container among the plurality of containers21is different. Therefore, when an external force is applied to the holder, it is possible to change the movable direction of the power storage device housed in each container and the ease of deformation of the container.

According to upper holder20, similarly to upper holder10described above, the impact of power storage module5can be absorbed by upper holder20, and the deformation of power storage device6can be suppressed.

Upper holder30as an example of the exemplary embodiment will be described with reference toFIG.4.FIG.4is a cross-sectional view of upper holder30.

In upper holder30, holes35are formed at equal intervals (for example, at 120° intervals) along the periphery of container31in plan view. In the edge of upper holder30, hole35A is formed at a position where a distance between the edge and container31is minimized. Hole35A is smaller in opening area than other holes35. Configurations (wall32and the like) other than these are similar to those of upper holder10described above, and thus the description thereof is omitted. With such a configuration, in the container of the lowermost row inFIG.4, holes35and holes35A are non-uniformly arranged with respect to the circumferential direction of the container. When holes35and holes35A are arranged non-uniformly, the power storage device can easily move to a place where the holes are arranged densely. Therefore, the container in the lowermost row easily restricts the moving direction when an external force is applied to upper holder30. Further, inFIG.3, it can be said that the container in the lowermost row is more fragile than the container in the uppermost row between the container in the uppermost row and the container in the lowermost row.

According to upper holder30, similarly to upper holder10described above, the impact of power storage module5can be absorbed by upper holder30, and the deformation of power storage device6can be suppressed.

Upper holder40as an example of the exemplary embodiment will be described with reference toFIG.5.FIG.5is a cross-sectional view and a partially enlarged view illustrating upper holder40.

Upper holder40has a bottom surface facing lower holder7, and has a plurality of containers41formed on the bottom surface and in which part near upper ends of the respective power storage devices6are housed, and holes45formed so as to penetrate the containers41along the axis of the power storage device. Container41includes wall42having an inner peripheral surface facing a side peripheral surface of power storage device6.

Holes45are formed at equal intervals (for example, at 180° intervals) along the periphery of container41in plan view. Hole45is a through hole having a substantially triangular prism shape, and is formed such that each corner45R faces each adjacent container41. Corner45R is formed in an R shape. One of corners45R communicates with adjacent container41to form communicating part45S. In the circumferential direction of hole45, the portion where communicating part45S is formed can be more easily deformed than the portion where communicating part45S of hole45is not provided. Therefore, in hole45, the ease of deformation of hole45can be controlled by the presence or absence of communicating part45S. Further, communicating part45S may be narrower in hole45than a portion other than communicating part45S (may have a shape narrowed by communicating part45S). With such a configuration, a holding force of power storage device6of container45in a normal state is enhanced. In addition, hole45A formed along the edge located at the outermost periphery of the bottom surface of upper holder10among holes45has an opening area smaller than that of other holes45.

The distance between container41and hole45in plan view is smaller than the distance between container41and adjacent container41in plan view or the distance between container41and the edge of upper holder40in plan view. In other words, a region between corner45R of hole45and container41in plan view of upper holder40is the thinnest portion of upper holder40.

According to upper holder40, similarly to upper holder10described above, the impact of power storage module5can be absorbed by upper holder40, and the deformation of power storage device6can be suppressed.

Upper holder50as an example of the exemplary embodiment will be described with reference toFIG.6.FIG.6is a cross-sectional view and a partially enlarged view illustrating upper holder50.

Upper holder50has a bottom surface facing lower holder7, and a plurality of containers51formed on the bottom surface and housing near upper ends of respective power storage devices6are formed. A part near an upper end of power storage device6is fitted to container51. With such a configuration, the part near the upper end of power storage device6is held by upper holder50.

Container51includes a ceiling having a bottom surface facing an upper end surface of power storage device6and wall52having an inner peripheral surface facing a side peripheral surface of power storage device6. Wall52includes recess55formed along the axis of the power storage device.

The recesses55are formed at equal intervals (for example, at 60° intervals) along the periphery of container51in plan view. In other words, since containers51(power storage devices6) are arranged in a staggered manner, recess55is formed between three containers51in plan view. Recess55has a substantially semi-elliptical shape and is formed so as to face the outside of container51. In addition, hole55A is formed along an edge located at the outermost periphery of the bottom surface of upper holder50.

The distance between recess55and adjacent recess55in plan view is shorter than the distance between container51and adjacent container51in plan view or the distance between container51and the edge of upper holder50in plan view. In other words, the region between recess55and recess55adjacent in plan view of upper holder50is the thinnest portion of upper holder50.

According to upper holder50, when an impact is applied from a side surface of power storage module5, a region between recess55and recess55adjacent to each other, which is the thinnest in plan view of upper holder50, is broken as a fracture starting point, and entire upper holder50is deformed. With such a configuration, an impact of power storage module5can be absorbed by upper holder50and hence, deformation of power storage device6can be suppressed. As a result, the safety of power storage module5is not impaired. In addition, in some of the containers of upper holder50, recess55is arranged unevenly. By arranging the recesses unevenly in this manner, a portion where the recesses are densely arranged is more easily deformed than a portion where the recesses are sparse. By controlling the density of the recesses, the direction in which container51is deformed and the direction in which power storage device6moves may be controlled.

Upper holder60as an example of the exemplary embodiment will be described with reference toFIG.7.FIG.7is a cross-sectional view of upper holder60.

In upper holder60, gap66is formed at an edge. Gap66is formed in a portion where the thickness of a region such as a corner of upper holder60increases. Other configurations (container61, wall62, hole65, hole65A, and the like) are the same as those of upper holder10described above, and thus the description thereof will be omitted.

According to upper holder60, similarly to upper holder10described above, the impact of power storage module5can be absorbed by upper holder20, and the deformation of power storage device6can be suppressed. Further, as compared with upper holder10, an edge of upper holder60protrudes outward due to gap66. Since the edge protrudes, rigidity of the upper holder is enhanced. Further, since gap66is provided, when a force is applied from the outside of upper holder60, it is possible to preferentially break before the force is transmitted to the container, and to perform a function of weakening the force transmitted to the container (buffering function). Further, gap66provided on the side opposite to the side where the external force is applied can be a space where power storage device6which moves in upper holder60by the external force enters gap66to weaken the force applied to power storage device6.

Upper holder70as an example of the exemplary embodiment will be described with reference toFIG.8.FIG.8is a cross-sectional view of upper holder70.

In upper holder70, fixing part77is formed at an edge. Fixing part77is a portion to which a bolt, a nut, or the like for fixing upper holder70is screwed. Fixing part77is suitably provided, for example, in a region such as a corner of upper holder70. In upper holder70, gap76having the same function as upper holder60is formed. Gap76is formed in a portion having a large thickness such as a region between fixing part77of upper holder70and storage portion71. Other configurations (container71, wall72, hole75, hole75A, and the like) are the same as those of upper holder10described above, and thus the description thereof will be omitted.

According to upper holder70, similarly to upper holder10described above, the impact of power storage module5can be absorbed by upper holder20, and the deformation of power storage device6can be suppressed. Further, fixing part77has higher rigidity than upper holder70in which a portion of upper holder10where fixing part77is provided is recessed. In addition, the rigidity of upper holder70can be further enhanced by using a material having high rigidity different from that of the upper holder for the threaded portion for screwing the bolt and the nut into fixing part77.

Upper holder80as an example of the exemplary embodiment will be described with reference toFIG.9.FIG.9is a cross-sectional view of upper holder80.

Upper holder80has a bottom surface facing lower holder7, and has a plurality of containers81formed on the bottom surface and in which parts near upper ends of the respective power storage devices6are housed, and holes85formed so as to penetrate the containers81along the axis of the power storage device. In this example, eight containers81are formed so as to surround the periphery of one container81. Container81includes wall82having an inner peripheral surface facing a side peripheral surface of power storage device6.

Holes85are formed at equal intervals (for example, at 90° intervals) along the periphery of the container81in plan view. Hole85is a through hole having a substantially quadrangular prism shape, and is formed such that each corner85R faces each adjacent container81. Corner85R is formed in an R shape.

The distance between container81and hole85in plan view is smaller than the distance between container81and adjacent container81in plan view or the distance between container81and the edge of upper holder80in plan view. In other words, a region between corner85R of hole85and container81in plan view of upper holder80is the thinnest portion of upper holder80.

According to upper holder80, similarly to upper holder10described above, the impact of power storage module5can be absorbed by upper holder80, and the deformation of power storage device6can be suppressed.

The hole described in the above embodiment is preferably a through hole, but may be a hole having a bottom. In addition, the hole arranged at the edge of the holder may not have a shape in which the width of the portion near the container (dimension in the direction perpendicular to the direction from the hole toward the container) is long. The part near the edge and the part near the container may have the same width. The width of the part near the edge may be larger than the width of the part near the container. The shape of the inner edge of the corner of the hole may not be an R shape. For example, the corner may be constituted by a plurality of straight lines and may have a vertex by two adjacent straight lines.

Note that the present invention is not limited to the above-described exemplary embodiments and modified examples thereof, and it is a matter of course that various changes and improvements can be made within the scope of the matters described in the claims of the present application.

REFERENCE MARKS IN THE DRAWINGS