JP2017183007A - Power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device which can maintain a fixed state even if torque is applied to an electrode terminal.SOLUTION: An electrode terminal 41 of a secondary battery comprises: a connection member 42 having a cylindrical part 44; and a terminal member 52 fixed to the connection member 42. The terminal member 52 includes: an electrode pole 53 press-fitted into the connection member 42; and a shaft part 54 protruding from the electrode pole 53 and provided with a threaded part 54a on its circumferential face. The connection member 42 includes a press-fit recess 45 into which the electrode pole 53 is press-fitted. The connection member 42 further includes, on the cylindrical part 44, a protrusion 46 having a structure in which a plurality of points are brought into press-contact with the circumferential face of the electrode pole 53 along the axial direction of the electrode pole 53.SELECTED DRAWING: Figure 3

Description

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

  A vehicle such as an EV (Electric Vehicle) or a PHV (Plug in Hybrid Vehicle) is equipped with a secondary battery such as a lithium ion battery as a power storage device that stores power supplied to an electric motor serving as a prime mover. This type of secondary battery is disclosed in Patent Document 1, for example. As shown in FIG. 8, the battery of Patent Document 1 includes a terminal member 81 that is electrically connected to an electrode assembly (not shown). The terminal member 81 passes through a hole 82 b existing in the lid portion 82 a of the casing 82 and protrudes outside the casing 82.

  The terminal member 81 includes a plate-like current collecting component 83 disposed in the housing 82 and a terminal component 84 as an electrode terminal fixed to the current collecting component 83. The terminal component 84 includes a clinch portion 85 at one end in the axial direction. The terminal component 84 includes a roughened surface forming portion 84 a on the outer peripheral surface of the clinching portion 85. The terminal component 84 includes a connection portion 84b on the other end side in the axial direction, and the connection portion 84b is a male screw. The batteries are connected to each other by fastening the bus bar to the connecting portion 84b with a nut.

  The current collecting component 83 includes a press-fitting hole 83a into which the roughened surface forming portion 84a of the terminal component 84 is press-fitted. Then, the clinch portion 85 is press-fitted into the press-fitting hole 83a, and the current collecting component 83 and the terminal component 84 are fixed to ensure conductivity.

JP 2010-97732 A

  By the way, in order to fasten the bus bar to the terminal component 84, when the nut is screwed into the connection portion 84b of the terminal component 84, the terminal component 84 is rotated by the torque applied to the terminal component 84, and the clinch portion 85 and the press-fit hole 83a There is a possibility that the fixed state of the is destroyed.

  An object of the present invention is to provide a power storage device that can maintain a fixed state even when torque is applied to an electrode terminal.

  A power storage device for solving the above problems includes a case, an electrode assembly housed in the case, a conductive member joined to the electrode assembly, and an electrode electrically connected to the conductive member A power storage device including a terminal, wherein the electrode terminal includes a connecting member including a cylindrical portion, and a terminal member fixed to the connecting member, and the terminal member includes the cylindrical portion. And a shaft portion that protrudes from the pole column portion and has a screw portion on the peripheral surface, and the connecting member extends along the circumferential direction of the peripheral surface of the pole column portion. The gist of the invention is to provide the cylindrical portion with a protrusion having a structure in pressure contact with at least three locations along the axial direction of the pole portion.

  According to this, in the electrode terminal in which the pole column portion is fixed to the connecting member, in addition to the inner peripheral surface of the cylindrical portion, the protruding portion protruding from the inner peripheral surface is pressed against the peripheral surface of the pole column portion. Yes. In the protruding portion, the tightening force with respect to the pole portion is stronger than the inner peripheral surface of the tubular portion. There are at least three places where the tightening force is high in the circumferential direction of the cylindrical portion. For this reason, the terminal member can be firmly fixed to the connection member. As a result, since the bus bar is fastened to the shaft portion of the terminal member, when the screw member is screwed to the shaft portion, the terminal member can be prevented from rotating even if torque is applied to the terminal member. The fixed state can be maintained.

Moreover, about the electrical storage apparatus, the protrusion dimension from the internal peripheral surface of the said cylindrical part in the said protrusion part which exists in at least three places is the same.
According to this, the central axis of a terminal member can be located on the central axis of a connection member because the protrusion part which exists in at least three places press-contacts with the surrounding surface of a pole column part.

Moreover, about the electrical storage apparatus, the said protrusion part exists over the whole axial direction of the said cylindrical part.
According to this, the area of the ridge part press-contacted to the polar column part can be increased, and the tightening force on the polar column part can be further increased.

  The power storage device is a secondary battery.

  According to the present invention, it is possible to maintain a fixed state even when torque is applied to the electrode terminals.

The disassembled perspective view which shows the secondary battery of embodiment. The perspective view which shows an electrical storage module. The longitudinal cross-sectional view which shows the electrode terminal vicinity of a secondary battery. (A) is a figure which shows the state before pressing a terminal member in a connection member, (b) is sectional drawing which shows a cylindrical part and a protrusion part. The plane sectional view showing the state where the terminal member was press-fitted into the connecting member. (A) is a figure which shows the metal structure of the protrusion part before pressing a terminal member in a connection member, (b) is a figure which shows the metal structure of the protrusion part in the state which pressed the terminal member in the connection member, (c) () Is a figure which shows the metal structure of the cylindrical part located between protrusion parts. Sectional drawing which shows another example of a terminal structure. The figure which shows background art.

Hereinafter, an embodiment in which the power storage device is embodied as a secondary battery will be described with reference to FIGS.
As shown in FIG. 1 or FIG. 2, the secondary battery 10 as the power storage device includes a case 12. The secondary battery 10 includes an electrode assembly 20 accommodated in the case 12 and an electrolyte solution (not shown). The case 12 includes a rectangular parallelepiped case main body 13 having an opening 13 d and a rectangular flat plate-shaped lid 14 that closes the opening 13 d of the case main body 13. Both the case body 13 and the lid 14 are made of metal (for example, stainless steel or aluminum). The secondary battery 10 is a square lithium ion battery.

  Although not shown in detail, the electrode assembly 20 includes a rectangular sheet-like positive electrode 21 and a rectangular sheet-like negative electrode 22. The positive electrode 21 and the negative electrode 22 are of a laminated type in which a separator 23 is interposed between them. The positive electrode 21 includes a rectangular metal foil for a positive electrode (in this embodiment, an aluminum foil) and a positive electrode active material layer present on both surfaces of the metal foil for a positive electrode. The negative electrode 22 includes a rectangular metal foil for negative electrode (copper foil in the present embodiment) and a negative electrode active material layer present on both surfaces of the metal foil for negative electrode.

  The positive electrode 21 has a positive electrode current collecting tab 21c having a shape protruding from a part of one side (long side). The negative electrode 22 has a negative electrode current collecting tab 22c having a shape protruding from a part of one side (long side). The positive electrode 21 is laminated so that the respective positive electrode current collecting tabs 21c are arranged in a row along the lamination direction. The negative electrode 22 is laminated such that the respective negative electrode current collecting tabs 22c are arranged in a row along the laminating direction so as not to overlap the positive electrode current collecting tabs 21c. The plurality of positive electrode current collecting tabs 21 c are collected in a range from one end to the other end in the stacking direction of the electrode assembly 20. Similarly, the plurality of negative electrode current collecting tabs 22c are also collected in a range from one end to the other end in the stacking direction of the electrode assembly 20.

  The secondary battery 10 includes a positive electrode tab group 21d in which positive electrode current collection tabs 21c are collected. The secondary battery 10 includes a positive electrode conductive member 33 bonded to the positive electrode tab group 21d. The secondary battery 10 includes a negative electrode tab group 22d in which the negative electrode current collecting tabs 22c are collected. The secondary battery 10 includes a negative electrode conductive member 37 joined to the negative electrode tab group 22d.

  The secondary battery 10 includes a positive electrode terminal 41 joined to the positive electrode conductive member 33. The secondary battery 10 includes a negative electrode terminal 41 joined to the negative electrode conductive member 37. The positive electrode terminal 41 and the negative electrode terminal 41 exchange electricity with the electrode assembly 20. The electrode terminal 41 of each pole passes through the inside and outside of the case 12 with a lid 14 and is fixed to the lid 14.

Next, the electrode terminal 41 will be described. The positive electrode terminal 41 and the negative electrode terminal 41 have the same shape.
As shown in FIG. 3, the electrode terminal 41 includes a bolt-shaped connection member 42 and a terminal member 52 fixed to the connection member 42. In the positive electrode terminal 41, the connection member 42 is made of pure aluminum. In the negative electrode terminal 41, the connecting member 42 is made of pure copper. The positive and negative terminal members 52 are made of an iron-based high-strength steel alloy such as carbon steel, chrome steel, nickel chrome steel, chrome molybdenum steel, or nickel chrome molybdenum steel. The iron-based alloy that is the material of the terminal member 52 has higher hardness than pure aluminum that is the material of the positive connection member 42 and pure copper that is the material of the negative connection member 42.

  As shown in FIG. 1 or FIG. 3, the connection member 42 has a square plate-like base 43. The positive electrode terminal 41 has a base 43 bonded to the positive electrode conductive member 33, and the negative electrode terminal 41 has a base 43 bonded to the negative electrode conductive member 37.

  The connection member 42 includes a cylindrical tubular portion 44 erected from the center of the base portion 43. The tubular portion 44 extends from the base portion 43 in the electrode terminal 41 in the penetrating direction of the lid 14. The connection member 42 includes a male screw 44 a on the outer peripheral surface of the cylindrical portion 44. In the connection member 42, the direction in which the central axis L of the cylindrical portion 44 extends is defined as the axial direction. The connection member 42 includes a press-fit recess 45 in the cylindrical portion 44. The press-fit recess 45 has a shape that is recessed in a circular shape from the distal end surface of the cylindrical portion 44 along the axial direction.

  As shown in FIG. 4A or FIG. 4B, the connecting member 42 includes a plurality of protrusions 46 in the cylindrical portion 44. The plurality of protrusions 46 exist at equal intervals in the circumferential direction of the tubular portion 44. Each protruding portion 46 has a shape protruding from the inner peripheral surface of the cylindrical portion 44 toward the central axis L. Further, each protrusion 46 exists along the axial direction of the tubular portion 44 from the distal end to the proximal end of the tubular portion 44 and over the entire axial direction of the tubular portion 44. In each protrusion 46, the protrusion dimension from the inner peripheral surface of the tubular portion 44 toward the central axis L is defined as the height. The height of the protrusion 46 is the same for all protrusions 46. In addition, the dimension between the projecting ridge portions 46 facing in the radial direction of the cylindrical portion 44 is defined as an inner diameter r of the cylindrical portion 44.

  As shown in FIG. 1 or FIG. 4A, the terminal member 52 is disposed outside the case 12. The terminal member 52 includes a cylindrical pole column portion 53 and a shaft portion 54 protruding along the direction in which the central axis M of the pole column portion 53 extends. A diameter r <b> 1 of the pole portion 53 is larger than an inner diameter r of the protrusion 46 in the tubular portion 44. The shaft portion 54 includes a screw portion 54a threaded on the outer peripheral surface.

  As shown in FIG. 3, the pole portion 53 of the terminal member 52 is press-fitted into the cylindrical portion 44 of the connection member 42. In other words, the pole column portion 53 of the terminal member 52 is in a state of being press-fitted into the tubular portion 44. In the press-fitted state, the inner peripheral surface of the cylindrical portion 44 including all the protruding portions 46 is plastically deformed in the diameter increasing direction, and the inner peripheral surface of the cylindrical portion 44 including all the protruding portions 46 is the polar column portion. The circumferential surface of 53 is in pressure contact over the entire circumferential direction. In particular, the protrusion 46 is crushed so that the height is lowered. Further, the vicinity of the protruding end of the protrusion 46 is plastically flowed along the press-fitting direction of the pole column 53.

By this pressure contact, the rotation of the pole portion 53 and the withdrawal from the connection member 42 are restricted, and the terminal member 52 is fixed to the connection member 42. Further, the connection member 42 and the terminal member 52 are electrically connected by pressure contact. Further, the central axis M of the pole column portion 53 in the terminal member 52 is located on the central axis L of the cylindrical portion 44 in the connecting member 42. +
As indicated by an arrow Y in FIG. 5, a tightening force acts on the peripheral surface of the pole column portion 53 from the inner peripheral surface of the cylindrical portion 44 and all the protrusions 46. Since all the ridges 46 have the same height, the distribution of the tightening force is the same in all the ridges 46. Further, the tightening force is weaker than the tightening force at the protrusion 46 in the portion between the protrusions 46 adjacent to each other in the circumferential direction of the tubular portion 44.

  FIG. 6A schematically shows the metal structure of the protrusion 46 before the pole portion 53 is press-fitted into the tubular portion 44. Prior to press-fitting, the ridges 46 constitute a metal crystal grain layer α in which no plastic flow occurs. FIG. 6B schematically shows the metal structure in the vicinity of the protruding end of the protrusion 46 after the pole column portion 53 is press-fitted into the tubular portion 44. After the press-fitting, the protrusion 46 constitutes the fine crystal grain layer β in which the metal crystal grains are broken. Further, the outer peripheral side of the ridge 46 constitutes a plastic fluidized bed γ in which metal crystal grains flow in the press-fitting direction. The outer peripheral side of the plastic fluidized bed γ constitutes a metal crystal grain layer α in which the metal crystal grains are not plastically deformed.

  FIG. 6C schematically shows the metal structure of the portion between the protrusions 46 after the pole column portion 53 is press-fitted into the tubular portion 44. Compared with the vicinity of the protruding end of the protruding portion 46, the portion between the protruding portions 46 is less damaged by metal crystal grains and constitutes the plastic fluidized bed γ. The outer peripheral side of the plastic fluidized bed γ constitutes a metal crystal grain layer α in which the metal crystal grains are not plastically deformed.

  As shown in FIG. 1 or FIG. 3, the secondary battery 10 includes a resin terminal cover 50 attached to the base 43. The terminal cover 50 electrically insulates the case 12 and the electrode terminals 41 of each polarity. The secondary battery 10 includes an O-ring 56 supported on the base 43. The O-ring 56 is in a state surrounding the cylindrical portion 44. A part of the cylindrical portion 44 and the shaft portion 54 protrude (expose) to the outside of the case 12 through the insertion hole 14 b of the lid 14. The base 43 of the electrode terminal 41 is located in the case 12. The secondary battery 10 includes a cylindrical insulating member 19. The insulating member 19 insulates the inner peripheral surface of the insertion hole 14 b of the lid 14 from the outer peripheral surface of the cylindrical portion 44.

  A nut 55 is screwed onto the male screw 44 a of the connecting member 42. The flange portion 19a of the insulating member 19 is sandwiched between the lid 14 and the nut 55, and the nut 55 and the lid 14 are insulated by the flange portion 19a.

  When the nut 55 is screwed onto the male screw 44 a of the cylindrical portion 44, the flange portion 19 a, the lid 14, the O-ring 56, and the terminal cover 50 are narrowed between the nut 55 and the base portion 43, and the electrode A terminal 41 is fastened to the lid 14. The O-ring 56 is in close contact with the inner surface of the lid 14 and the base portion 43 in a compressed state, and seals the periphery of the insertion hole 14b.

  As shown in FIG. 2, each secondary battery 10 includes a positive electrode terminal 41 of the secondary battery 10 adjacent to the negative electrode terminal 41 of the secondary battery 10 adjacent to the negative electrode terminal 41 of the secondary battery 10 adjacent to the positive electrode electrode 41. A power storage module 71 is configured by the plurality of secondary batteries 10 connected to the terminals 41 via bus bars 60.

  As shown in FIG. 1, the bus bar 60 that electrically connects the secondary batteries 10 has a rectangular plate shape. The bus bar 60 has a pair of insertion portions 60a. A nut 61 as a screw member for fixing the bus bar is screwed to the male screw of the shaft portion 54 of the terminal member 52. The bus bar 60 is fixed to the terminal member 52 by the nut 61.

Next, a method for integrating the connecting member 42 and the terminal member 52 will be described.
In order to press-fit the pole column portion 53 of the terminal member 52 into the press-fit recess 45 of the tubular portion 44, the pole column portion 53 is disposed at the opening end of the press-fit recess 45. Then, the connection member 42 is gripped by a fixing jig (not shown) of the press-fitting device, the terminal member 52 is gripped by a movable jig, and the terminal member 52 is surrounded by a plurality of protrusions 46 of the connection member 42. Press into the space. Then, when the entire pole column portion 53 is press-fitted into the press-fit recess 45, the press-fitting operation is finished.

According to the above embodiment, the following effects can be obtained.
(1) In the electrode terminal 41 in which the terminal member 52 is fixed to the connection member 42, the plurality of protrusions 46 are in pressure contact with the peripheral surface of the pole column portion 53 in addition to the inner peripheral surface of the cylindrical portion 44. In each protrusion 46, the tightening force with respect to the peripheral surface of the pole column portion 53 is stronger than the inner peripheral surface of the tubular portion 44, and the terminal member 52 can be firmly fixed to the connection member 42. As a result, in order to fasten the bus bar 60 to the terminal member 52, when the nut 61 is screwed to the shaft portion 54 of the terminal member 52, the terminal member 52 can be restricted from rotating even if torque is applied to the terminal member 52. The connection state between the connecting member 42 and the terminal member 52 can be maintained.

  Further, the inner peripheral surface of the cylindrical portion 44 and the plurality of protrusions 46 are in pressure contact with the polar column portion 53 of the terminal member 52. For this reason, the contact area of the connection member 42 and the terminal member 52 can be ensured, and the conductivity of the connection member 42 and the terminal member 52 can be ensured.

  (2) In the positive electrode terminal 41, the connecting member 42 is made of pure aluminum, and in the negative electrode terminal 41, the connecting member 42 is made of pure copper. Pure aluminum and pure copper are soft metals and are easily plastically deformed. On the other hand, the terminal member 52 is made of an iron-based high-strength steel alloy and has high strength. For this reason, when the polar column portion 53 is press-fitted into the tubular portion 44, the inner peripheral surface of the tubular portion 44 and each protrusion 46 are plastically deformed, and the tubular portion 44 can be prevented from cracking and the polar column. The portion 53 can be pressed. Therefore, a lithium ion secondary battery using pure aluminum for the positive electrode and pure copper for the negative electrode is suitable for adopting a structure in which the terminal member 52 is press-fitted into the connecting member 42.

  (3) In the connection member 42, the height of all the protrusions 46 is the same. For this reason, the central axis M of the terminal member 52 can be positioned on the central axis L of the connecting member 42. Therefore, the position of the shaft portion 54 is not easily displaced, and the shaft portion 54 can be inserted without making the insertion portion 60a of the bus bar 60 have a large diameter. As a result, it is possible to eliminate an increase in resistance of the bus bar 60 due to an increase in the diameter of the insertion portion 60a.

  (4) The protruding portion 46 extends from the distal end to the proximal end along the axial direction of the cylindrical portion 44. For this reason, the area of the protrusion 46 that presses against the pole column 53 press-fitted into the cylindrical portion 44 can be increased, and the tightening force on the pole column can be further increased.

  (5) The pole column portion 53 of the terminal member 52 is press-fitted into the cylindrical portion 44 of the connection member 42, and the pole column portion 53 is press-fitted in the entire axial direction of the cylindrical portion 44. Therefore, for example, compared with the case where the pole column part 53 is press-fitted within the thickness of the conductive member, a longer press-fitting length can be secured, and the terminal member 52 can be firmly fixed to the connection member 42.

In addition, you may change the said embodiment as follows.
The plurality of protrusions 46 may not be present from the distal end along the axial direction of the tubular portion 44 to the entire proximal end, and may be shorter than the length along the axial direction of the tubular portion 44. . For example, the protruding portion 46 may be present behind the axial tip of the cylindrical portion 44 and may be shorter than the embodiment.

Each ridge 46 may be divided into a plurality along the axial direction of the tubular portion 44.
If the central axis M of the terminal member 52 can be positioned on the central axis L of the connecting member 42 by the plurality of protruding portions 46, the number of the protruding portions 46 is three, four, five, and six. But you can.

  In the terminal member 52, the shaft portion 54 may be cylindrical, and a threaded portion 54a of a female screw may be provided on the inner peripheral surface of the shaft portion 54. In this case, when the bus bar 60 is fastened to the shaft portion 54, a bolt inserted as a screw member into the insertion portion 60a of the bus bar 60 is screwed into the screw portion made of a female screw.

  The terminal structure of the secondary battery 10 may be the form shown in FIG. The terminal structure includes a conductive member 62 connected to the tab groups 21d and 22d of each polarity (only the negative tab group 22d is shown in FIG. 7), joined to the conductive member 62, penetrates the lid 14, and goes out of the case 12. A protruding lead terminal 63, an electrode terminal 64 disposed on the outer surface of the lid 14, and a terminal connecting member 65 that connects the electrode terminal 64 and the lead terminal 63 may be provided. The lead terminal 63 is insulated from the inner surface of the lid 14 by the inner insulating member 66 and is insulated from the outer surface of the lid 14 by the outer insulating member 67. Further, the electrode terminal 64 is insulated from the outer surface of the lid 14 by the outer insulating member 67. The outer insulating member 67 is positioned on the lid 14, and the terminal connection member 65 is positioned on the outer insulating member 67. The electrode terminal 64 is bonded to the terminal connection member 65 and positioned on the lid 14. The electrode terminal 64 is electrically connected to the conductive member 62 via the lead terminal 63 and the terminal connection member 65.

The electrode terminal 64 may be constituted by the connection member 68 and the terminal member 52, and three or more protrusions 68 a may be provided on the cylindrical portion 70 of the connection member 68.
The electrode assembly 20 may be a wound type in which one strip-like positive electrode and one strip-like negative electrode are wound around a winding axis in a state where they are insulated by a separator.

The power storage device may be another power storage device such as an electric double layer capacitor.
In the embodiment, the secondary battery 10 is a lithium ion secondary battery, but is not limited thereto, and may be another secondary battery such as a nickel hydride battery. In short, any ion may be used as long as ions move between the positive electrode active material layer and the negative electrode active material layer and transfer charge.

Next, the technical idea that can be grasped from the above embodiment and other examples will be described below.
(1) The power storage device in which the positive electrode is made of pure aluminum and the negative electrode is made of pure copper.

  (2) The power storage device, wherein the terminal member is made of an iron-based high-strength steel alloy.

  DESCRIPTION OF SYMBOLS 10 ... Secondary battery as a power storage device, 12 ... Case, 20 ... Electrode assembly, 33 ... Positive electrode conductive member, 37 ... Negative electrode conductive member, 41, 64 ... Electrode terminal, 42, 68 ... Connection member, 44, 70 ... Cylindrical part, 46, 68a ... ridge part, 52 ... terminal member, 53 ... polar pole part, 54 ... shaft part, 54a ... screw part, 62 ... conductive member.

Claims (4)

Case and
An electrode assembly housed in the case;
A conductive member joined to the electrode assembly;
An electrical storage device comprising an electrode terminal electrically connected to the conductive member,
The electrode terminal is
A connecting member comprising a tubular portion;
A terminal member fixed to the connection member,
The terminal member includes a pole portion in a state of being press-fitted into the cylindrical portion, and a shaft portion that protrudes from the pole column portion and includes a screw portion on a peripheral surface,
The connecting member is provided with a projecting portion having a structure in which the connecting portion is pressed along the axial direction of the pole column portion with respect to at least three locations along the circumferential direction of the peripheral surface of the pole column portion. A power storage device.   The power storage device according to claim 1, wherein the protrusions from the inner peripheral surface of the tubular part in the protrusions present at least at three locations are the same.   The power storage device according to claim 1, wherein the protruding portion exists over the entire axial direction of the cylindrical portion.   The power storage device according to any one of claims 1 to 3, wherein the power storage device is a secondary battery.

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