WO2016009786A1

WO2016009786A1 - Electricity storage device

Info

Publication number: WO2016009786A1
Application number: PCT/JP2015/067888
Authority: WO
Inventors: 寛恭西原; 元章奥田
Original assignee: 株式会社豊田自動織機
Priority date: 2014-07-16
Filing date: 2015-06-22
Publication date: 2016-01-21
Also published as: JP2016024844A; JP5928536B2

Abstract

This electricity storage device is provided with an electrode assembly, a case, and electrode terminals. The electrode assembly has a plurality of positive polarity electrodes, a plurality of negative polarity electrodes, and a plurality of separators, and the positive polarity electrodes and the negative polarity electrodes are stacked alternately, each time with a separator therebetween. The electrode assembly is housed in the case, and the electrode terminals are electrically connected to the electrode assembly and protrude outward from a wall part of the case. Each of the electrode terminals has a leading end and a base end in the axial direction thereof, and an outer peripheral surface. The leading end has an end face including a bus bar contact surface wherewith a bus bar can establish contact, and the outer peripheral surface has a threaded portion whereon a nut can be screwed from the external side of the case. The outer peripheral surface has a non-threaded portion where no threaded portion has been formed in the area between the leading end and a predetermined position that is distanced away from said leading end toward the base end in the axial direction of the electrode terminal.

Description

Power storage device

The present invention relates to a power storage device having an electrode terminal.

Vehicles such as EVs (Electric Vehicles) and PHVs (Plug Vehicles Hybrid Vehicles) are equipped with secondary batteries such as lithium-ion batteries as power storage devices that store power supplied to the motors. For example, the secondary battery described in Patent Document 1 includes an electrode assembly housed in a case and an electrode terminal electrically connected to the electrode assembly. The electrode terminal protrudes from the inside of the case toward the outside through a through hole provided in the lid of the case. The secondary battery is electrically connected by the bus bar by bringing the bus bar into contact with the end face of the tip of the electrode terminal and electrically connecting the electrode terminal and the bus bar.

JP 2014-102898 A

In order to reduce the contact resistance between the electrode terminal and the bus bar, it is desired to increase the contact area between the electrode terminal and the bus bar. In order to increase the contact area of the electrode terminal with the bus bar, for example, it is desirable to increase the flatness of the end face of the electrode terminal, that is, the end face (bus bar contact face) in contact with the bus bar.

In the secondary battery described in Patent Document 1, a thread portion is formed on the outer peripheral surface of the electrode terminal. In order to fix the electrode terminal to the case, a nut is screwed onto the screw portion of the electrode terminal from the outside of the case. Since the screw portion is formed at a portion including the tip in the axial direction of the electrode terminal, deformation or burring or the like occurs on the end surface of the tip of the electrode terminal due to processing of the screw portion, and the plane of the bus bar contact surface located on the end surface The degree may decrease.

An object of the present invention is to provide a power storage device that can suppress a decrease in flatness of a bus bar contact surface with processing of a threaded portion in an electrode terminal.

The power storage device that solves the above problems includes a plurality of positive electrodes, a plurality of negative electrodes, and a plurality of separators, and the positive electrode electrodes and the negative electrode electrodes are alternately stacked via the separators; A case in which the electrode assembly is accommodated, and an electrode terminal electrically connected to the electrode assembly and projecting outside from a wall portion of the case, the electrode terminal in the axial direction In addition to having a front end and a base end, the front end has an outer peripheral surface, and the front end has an end surface including a bus bar contact surface with which the bus bar can contact, and the outer peripheral surface is screwed with a nut from the outside of the case. The outer peripheral surface is in a range between the distal end and a predetermined position away from the distal end toward the base end in the axial direction of the electrode terminal. Part And a non-threaded portion which is not made.

The perspective view which shows a part of battery module in one Embodiment. The perspective view which shows the external appearance of the secondary battery of FIG. Sectional drawing which expands and shows the positive electrode terminal in the secondary battery of FIG. The enlarged view which expands and shows the part enclosed by the circle | round | yen of FIG. 3A.

Hereinafter, an embodiment of a power storage device will be described with reference to FIGS. 1 to 3B.
As shown in FIG. 1, a battery module 10 is configured by connecting adjacent secondary batteries 20 by a bus bar 11. The bus bar 11 has a flat plate shape and is fixed to each secondary battery 20 by a bolt 12.

As shown in FIG. 2, each power storage device, that is, the secondary battery 20 includes a case 21 and an electrode assembly 22 accommodated in the case 21. The electrode assembly 22 includes a plurality of positive electrodes, a plurality of negative electrodes, and a plurality of separators, and the positive electrodes and the negative electrodes are alternately stacked via the separators. Each positive electrode has a positive electrode active material layer, and each negative electrode has a negative electrode active material layer. The case 21 contains an electrolyte solution together with the electrode assembly 22. The case 21 includes a cylindrical case body 23 having a bottom and an opening, and a flat lid 24 that closes the opening. The electrode assembly 22 is inserted into the case main body 23 through the opening. Both the case main body 23 and the lid body 24 are made of metal (for example, made of stainless steel or aluminum). The secondary battery 20 of this embodiment is a lithium ion battery.

Two electrode terminals, that is, a negative electrode terminal 26 and a positive electrode terminal 27 are electrically connected to the electrode assembly 22. Hereinafter, the

terminals

26 and 27 will be described with reference to FIGS. 3A and 3B. Hereinafter, the configuration of the positive electrode terminal 27 will be described. However, since the negative electrode terminal 26 has the same configuration as the positive electrode terminal 27, the description of the negative electrode terminal 26 is omitted.

As shown in FIG. 3A, the positive electrode terminal 27 includes a plate-like base portion 31 located in the case 21 and a cylindrical pole column portion 32 that extends from the center of the base portion 31 in a direction orthogonal to the lid body 24. is doing. In other words, the pole portion 32 extends from the base portion 31 toward the outside of the case 21. Specifically, the pole portion 32 protrudes outside the case 21 through the through hole 25 provided in the wall portion of the case 21, that is, the lid body 24. A portion of the pole column portion 32 that protrudes to the outside of the case 21 is referred to as a “protruding portion”. An insulating ring 28 for insulating the positive electrode terminal 27 from the case 21 is disposed between the inner peripheral surface of the through hole 25 and the outer peripheral surface of the pole column portion 32 in the lid body 24.

The pole column portion 32 has a threaded portion, that is, a male threaded portion 33 on the outer peripheral surface. The pole portion 32 (specifically, the protruding portion) includes a base end 32a located on the base 31 side in the axial direction, and an end on the opposite side of the base end 32a, that is, a tip 32b protruding outside the case 21. And have. The tip 32b has a tip surface 32c. As shown in FIG. 3B, the male screw portion 33 has a base end from a predetermined position that is a predetermined distance away from the tip 32b to the base end 32a in the range from the tip 32b to the base end 32a of the pole column portion 32. It is formed in a range up to 32a. In other words, the non-threaded portion 33a where the male threaded portion 33 is not formed is located in the range from the tip 32b to the predetermined position on the outer peripheral surface of the pole column portion 32. The predetermined distance and the predetermined position are respectively set to a distance and a position at which the influence of deformation, burrs, and the like caused by processing of the male screw portion 33 does not reach the distal end surface 32c of the pole column portion 32.

The positive terminal 27 is fixed to the case 21 by screwing the nut 40 from the outside of the case 21 to the male screw portion 33 of the pole column portion 32. The non-threaded portion 33 a in the present embodiment is located on the outer peripheral surface of the portion of the pole column portion 32 that protrudes from the nut 40 outside the case 21. Further, the outer diameter of the non-threaded portion 33 a has the same size as the inner diameter of the nut 40, that is, the size that can be inserted into the nut 40. Further, the outer diameter of the non-threaded portion 33 a is constant along the axial direction of the positive electrode terminal 27.

The front end surface 32 c of the polar column part 32 is orthogonal to the axial direction of the polar column part 32. The pole column portion 32 has an insertion hole 34 extending from the distal end surface 32 c toward the base portion 31. The insertion hole 34 is a hexagonal engagement hole 35 that opens to the distal end surface 32 c of the pole column part 32, a screw hole 36 that is positioned closer to the base 31 than the engagement hole 35 and communicates with the engagement hole 35, It has. A hexagonal columnar jig is inserted into the engagement hole 35 so that the pole column 32 does not rotate with the nut 40 when the nut 40 is screwed into the pole column 32. The screw hole 36 has an internal thread on the inner peripheral surface.

When the bus bar 11 is fixed to the secondary battery 20, the bolt 12 penetrates the bus bar 11 and is screwed into the screw hole 36 in a state where the bus bar 11 and the tip end surface 32 c of the pole column portion 32 are in surface contact. That is, a portion of the tip end surface 32 c of the pole column portion 32 excluding the opening of the engagement hole 35 functions as a bus bar contact surface that contacts the bus bar 11.

Next, the effect | action of the secondary battery 20 of this embodiment is demonstrated.
The non-threaded portion 33a is located in the range from the distal end 32b to a predetermined position in the range from the distal end 32b to the proximal end 32a of the pole column portion 32 of each terminal 26, 27. For this reason, the processing of the male thread portion 33 on the pole column portion 32 is first performed from a predetermined position that is a predetermined distance away from the distal end 32b toward the proximal end 32a. Therefore, it is possible to suppress the influence of deformation, burrs, and the like caused by processing on the tip surface 32c existing at a position separating the non-threaded portion 33a from the male screw portion 33, and the flatness of the tip surface 32c is reduced. Can be suppressed.

When adjacent secondary batteries 20 are connected to each other by the bus bar 11, the bus bar 11 is placed on the front end surface 32 c of the negative electrode terminal 26 of one secondary battery 20 and the front end surface 32 c of the positive electrode terminal 27 of the other secondary battery 20. Then, the bolts 12 are screwed into the screw holes 36 of both

terminals

26 and 27, respectively. Thereby, the bus bar 11 is fixed to the

terminals

26 and 27 in surface contact with the distal end surfaces 32 c of the

terminals

26 and 27.

Therefore, according to the present embodiment, the following effects can be obtained.
(1) The non-screw part 33a is located in the range from the front-end | tip 32b to the predetermined position among the outer peripheral surfaces of the pole part 32 of each terminal 26,27. For this reason, it can suppress that the flatness of the front end surface 32c of the polar column part 32 falls with the process of the external thread part 33. FIG. Therefore, the contact area between the

terminals

26 and 27 and the bus bar 11 can be increased as compared with the case where the male screw portion 33 is formed in the portion including the tip 32 b in the pole column portion 32.

(2) The outer diameter of the non-threaded portion 33a is constant along the axial direction of the pole column portion 32. For this reason, the non-screw part 33a can be positioned in the pole column part 32, maintaining the area of the front end surface 32c in the pole column part 32 as large as the cross-sectional area of the pole column part 32 in a predetermined position.

(3) Since each of the

terminals

26 and 27 has the insertion hole 34 inside the pole column portion 32, the thickness in the direction (radial direction) perpendicular to the axial direction of the pole column portion 32 is small. For this reason, the polar column portion 32 is relatively easily deformed with the processing of the male screw portion 33, and the flatness of the distal end surface 32c is also likely to be relatively lowered. In the present embodiment, since the non-threaded portion 33a exists in the polar column portion 32, even if the polar column portion 32 has a configuration in which the flatness of the distal end surface 32c tends to be reduced, the distal end surface 32c. The reduction in flatness can be suppressed.

(4) The positive electrode terminal 27 uses aluminum or the like as a base material, and the surface of the base material of the terminal 27 may be plated with nickel or the like for the purpose of rust prevention. In the present embodiment, since the flatness of the distal end surface 32c of the pole column portion 32 can be improved as compared with the case where the male screw portion 33 is formed in a portion including the distal end 32b of the positive electrode terminal 27, the distal end surface 32c is moved to. Therefore, the cost required for the plating process on the positive electrode terminal 27 can be reduced.

In addition, the said embodiment can also be implemented with the following forms which changed this suitably.
○ In a state where the nut 40 is screwed into the male threaded portion 33 of the pole column portion 32, a part or all of the non-threaded portion 33a is located on the outer peripheral surface of the portion of the pole column portion 32 located inside the nut 40. May be. In other words, the non-threaded portion 33a may at least partially overlap the nut 40 in a state where the nut 40 is screwed into the male threaded portion 33. According to such a form, since the part which protrudes from the nut 40 among the protrusion parts of the pole part 32 decreases, the clearance gap between the nut 40 and the bus-bar 11 can be made small, and, thereby, the secondary battery 20. Can be reduced in size.

The shape of the portion corresponding to the non-threaded portion 33a in the pole column portion 32 is not limited to a cylindrical shape, and may be, for example, a rectangular cylindrical shape.
The outer diameter of the non-threaded portion 33 a may not be constant along the axial direction of the pole column portion 32. For example, the outer diameter of the non-threaded portion 33a changes so that the cross-sectional area of the pole column portion 32 in the portion corresponding to the non-threaded portion 33a increases from the distal end 32b of the polar column portion 32 toward the proximal end 32a. Also good.

In the above embodiment, both the negative electrode terminal 26 and the positive electrode terminal 27 have the non-threaded portion 33a in the pole column portion 32, but only one of the negative electrode terminal 26 and the positive electrode terminal 27 is The column part 32 may have a non-threaded part 33a.

The negative electrode terminal 26 and the positive electrode terminal 27 may protrude from the wall portion of the case 21 other than the lid 24, that is, from the wall portion of the case main body 23.
The secondary battery 20 is a lithium ion secondary battery, but is not limited thereto, and may be another secondary battery. In short, any secondary battery that transfers ions while transferring ions between the positive electrode active material layer and the negative electrode active material layer may be used.

○ The power storage device of the present invention may be a power storage device such as an electric double layer capacitor.

Claims

An electrode assembly having a plurality of positive electrodes, a plurality of negative electrodes, and a plurality of separators, wherein the positive electrodes and the negative electrodes are alternately stacked via the separators;
A case in which the electrode assembly is accommodated;
An electrode terminal electrically connected to the electrode assembly and projecting outward from the wall portion of the case,
The electrode terminal has a distal end and a proximal end in the axial direction, and an outer peripheral surface,
The tip has an end surface including a bus bar contact surface with which the bus bar can contact,
The outer peripheral surface has a threaded portion to which a nut can be screwed from the outside of the case,
The outer peripheral surface has a non-threaded portion in which the threaded portion is not formed in a range between the distal end and a predetermined position away from the distal end toward the proximal end in the axial direction of the electrode terminal. Power storage device.
The electric storage device according to claim 1, wherein an outer diameter of the non-threaded portion is constant along an axial direction of the electrode terminal.
The power storage device according to claim 1 or 2, wherein the power storage device is a secondary battery.