WO2015163230A1

WO2015163230A1 - Power storage device

Info

Publication number: WO2015163230A1
Application number: PCT/JP2015/061708
Authority: WO
Inventors: 耕二郎田丸; 元章奥田; 幹也栗田; 拓井上
Original assignee: 株式会社豊田自動織機
Priority date: 2014-04-24
Filing date: 2015-04-16
Publication date: 2015-10-29
Also published as: JPWO2015163230A1; JP6146536B2

Abstract

In the present invention, a power storage device is provided with an electrode assembly, a case, an injection hole, and a sealing member. The electrode assembly is provided with a plurality of positive electrodes that are provided with a positive electrode active material layer, a plurality of negative electrodes that are provided with a negative electrode active material layer, and a plurality of separators, the positive electrodes and the negative electrodes being alternatingly stacked with the separators interposed therebetween. The case is provided with a case wall, and the case houses the electrode assembly and an electrolyte in the interior. The injection hole passes through the case wall, and the sealing member seals the injection hole. The center point of the injection hole and the center point of the case wall are set apart from each other.

Description

Power storage device

This invention relates to a power storage device having a liquid injection hole for injecting an electrolyte into a case.

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. As described in Patent Document 1, for example, this type of secondary battery includes an electrode assembly having a plurality of positive electrodes, a plurality of negative electrodes, and a plurality of separators, and a case that houses the electrode assembly. ing. A plurality of positive electrodes provided with a positive electrode active material layer and a plurality of negative electrodes provided with a negative electrode active material layer are alternately laminated with a separator interposed therebetween. In addition, the case of the secondary battery includes a case wall, and the case wall is provided with a liquid injection hole for injecting an electrolytic solution into the case, and the liquid injection hole is a sealing member after the injection of the electrolytic solution. It is sealed by.

Japanese Patent No. 4298950

In the secondary battery, when the case is deformed, the curvature of the deformation differs depending on the position of the case wall. For this reason, when the liquid injection hole is positioned at a position where the curvature of deformation in the case wall is large, a gap is generated between the sealing member that seals the liquid injection hole and the case wall along with the deformation of the case, and sealing is performed. There is a possibility that the sealing property of the liquid injection hole by the stop member is lowered.

An object of the present invention is to provide a power storage device that can suppress the occurrence of a gap between a sealing member that seals a liquid injection hole and a case wall in accordance with deformation of the case.

A power storage device that solves the above problems includes a plurality of positive electrodes including a positive electrode active material layer, a plurality of negative electrodes including a negative electrode active material layer, and a plurality of separators, and the positive electrode and the negative electrode sandwich the separator. An electrode assembly alternately stacked in a sandwiched state, a case wall, a case containing the electrode assembly and the electrolyte therein, a liquid injection hole penetrating the case wall, and the liquid injection hole And a center point of the liquid injection hole and a center point of the case wall are shifted from each other.

The disassembled perspective view which shows the secondary battery in 1st Embodiment. The perspective view which shows the external appearance of the secondary battery of FIG. The perspective view which shows the component of the electrode assembly of FIG. The top view which shows the cover body of FIG. FIG. 5 is a sectional view taken along line 5-5 in FIG. FIG. 6 is a sectional view taken along line 6-6 in FIG. Sectional drawing which shows the rivet member of FIG. Sectional drawing of the rivet member periphery which shows the state by which the liquid injection hole was sealed by the rivet member. The top view which shows the secondary battery in 2nd Embodiment from a cover body. FIG. 10 is a sectional view taken along line 10-10 in FIG. 9; FIG. 11 is a sectional view taken along line 11-11 in FIG. 9;

(First embodiment)
Hereinafter, a first embodiment of a power storage device will be described with reference to FIGS.
As shown in FIGS. 1 and 2, the power storage device, that is, the secondary battery 10 includes an electrode assembly 12 and a case 11 that houses the electrode assembly 12. The case 11 also contains an electrolyte solution together with the electrode assembly 12. The case 11 includes a cylindrical case body 13 having a bottom and an opening 13a, and a flat lid 14 that closes the opening 13a. The electrode assembly 12 is inserted into the case body 13 through the opening 13a. Both the case main body 13 and the lid body 14 are made of metal (for example, made of stainless steel or aluminum). The secondary battery 10 of this embodiment is a prismatic battery having a rectangular body with a bottomed rectangular cylindrical case body 13 and a rectangular flat lid 14. Moreover, the secondary battery 10 of this embodiment is a lithium ion battery. A lid 14 is joined to the opening 13a of the case body 13 by welding (for example, laser welding). A welded portion W is formed around the opening 13a of the case body 13 and around the lid body 14 in contact with the opening 13a.

As shown in FIG. 3, the electrode assembly 12 includes a plurality of positive electrodes 21, a plurality of negative electrodes 25, and a plurality of separators 29, and the

electrodes

21 and 25 are alternately arranged with the separators 29 interposed therebetween. It is configured by stacking. The positive electrode 21, the negative electrode 25, and the separator 29 are rectangular.

Each positive electrode 21 includes a rectangular positive metal foil (for example, aluminum foil) 22 and a positive electrode active material layer 23 disposed on both surfaces of the positive metal foil 22 and having a positive electrode active material. Each positive electrode 21 has a positive electrode tab 24 that is a part of the positive electrode metal foil 22, and the positive electrode tab 24 protrudes from one side of the positive electrode 21, that is, a part of the edge 21 c.

Each negative electrode 25 includes a rectangular negative metal foil (for example, copper foil) 26 and a negative electrode active material layer 27 that is disposed on both surfaces of the negative electrode metal foil 26 and has a negative electrode active material. The negative electrode 25 has a negative electrode tab 28 that is a part of the negative electrode metal foil 26, and the negative electrode tab 28 protrudes from one side of the negative electrode 25, that is, a part of the edge 25 c.

The positive and

negative electrodes

21 and 25 are stacked so that the

tabs

24 and 28 having the same polarity are arranged in a row in the stacking direction, and the

tabs

24 and 28 having different polarities are not overlapped in the stacking direction.

As shown in FIG. 1, the positive electrode tab 24 and the negative electrode tab 28 protrude from the upper end (upper surface) 12 c which is one of the four ends (end surfaces) of the electrode assembly 12. The electrode 21 and the negative electrode 25 are laminated. The positive electrode tab 24 is bent in a state of being stacked in the stacking direction of the

electrodes

21 and 25. And the positive electrode tab 24 is electrically connected mutually by welding the location where the positive electrode tab 24 has overlapped. Similarly, the negative electrode tabs 28 are folded in an overlapped state, and the overlapping portions are electrically connected to each other by welding.

The secondary battery 10 includes a positive electrode terminal 15 electrically connected to the positive electrode tab 24 and a negative electrode terminal 16 electrically connected to the negative electrode tab 28. A part of the positive terminal 15 and a part of the negative terminal 16 are exposed to the outside of the case 11 through a through hole formed in the lid 14. Ring-shaped insulating members 17 a for insulating the

terminals

15 and 16 from the case 11 are attached to the positive terminal 15 and the negative terminal 16, respectively.

The case 11 includes a case wall, and the lid body 14 forms a part of the case wall and includes a pressure release valve 18. The pressure release valve 18 is cleaved when the pressure in the case 11 reaches an open pressure, which is a predetermined pressure, so that the pressure in the case 11 does not increase excessively, and the pressure in the case 11 is moved outside the case 11. Open. The release pressure of the pressure release valve 18 is set to a pressure at which the pressure release valve 18 can be cleaved before the case 11 itself or the joint between the case body 13 and the lid body 14 is cracked or broken. The pressure release valve 18 has a plate-like valve body 19 that is thinner than the plate thickness of the lid body 14. The lid body 14 has a recess 20 on a surface 14 a located outside the case 11. The valve body 19 is located at the bottom of the recess 20 and is formed integrally with the lid body 14. That is, the surface 19 a of the valve body 19 constitutes a part of the surface 14 a of the lid body 14.

As shown in FIG. 4, the pressure release valve 18 is located on the center line L 1 of the lid body 14 when the line passing through the midpoint of the length in the short direction of the lid body 14 is the center line L 1. . In this embodiment, the center point of the pressure release valve 18 is located on the center line L1 of the lid body 14, but the center point of the pressure relief valve 18 is located so as to be offset from the center line L1 of the lid body 14. Also good.

The lid body 14 has a back surface 14b located inside the case 11 and a circular liquid injection hole 14c. The liquid injection hole 14c communicates the front surface 14a and the back surface 14b and penetrates the lid body 14 in the thickness direction. In the lid body 14, when the line passing through the middle point in the longitudinal direction is the center line L 2 and the point where the center line L 1 and the center line L 2 intersect is the center point C 1, the liquid injection hole 14 c of the present embodiment. Center point C2 is deviated from the center line L1 and deviated from the center line L2. Furthermore, the area occupied by the opening surrounded by the outer peripheral edge 14d of the liquid injection hole 14c of the present embodiment, that is, the opening area of the liquid injection hole 14c is deviated from the center line L1 and deviated from the center line L2. . That is, the center point C2 and the opening area of the liquid injection hole 14c are shifted from the center point C1 of the lid body 14. As will be described later, the liquid injection hole 14 c is sealed by a sealing member, that is, a rivet member 30. For this reason, in a state where the liquid injection hole 14 c is sealed by the rivet member 30, the opening area of the liquid injection hole 14 c is blocked by the rivet member 30.

As shown in FIG. 5, the liquid injection hole 14 c is located between the protruding position of the positive electrode tab 24 and the protruding position of the negative electrode tab 28 at the upper end 12 c of the electrode assembly 12. More specifically, when viewed from a direction orthogonal to the direction in which the protruding position of the positive electrode tab 24 and the protruding position of the negative electrode tab 28 are aligned (that is, the longitudinal direction of the lid body 14), the liquid injection hole 14 c has the protruding position of the positive electrode tab 24. It is located between the protruding position of the negative electrode tab 28. For example, the liquid injection hole 14 c is located between the protruding position of the positive electrode tab 24 and the protruding position of the negative electrode tab 28 as viewed from the direction along the protruding direction of the

tabs

24 and 28.

As shown in FIG. 6, the liquid injection hole 14 c overlaps the pressure release valve 18 when viewed from the longitudinal direction of the lid body 14.
The liquid injection hole 14c is sealed by the rivet member 30, and leakage of gas and electrolyte from the case 11 is prevented.

Next, the rivet member 30 before being inserted into the liquid injection hole 14c will be described.
As shown in FIG. 7, the rivet member 30 includes a hollow cylindrical body portion 31, an annular flange 32, a mandrel 40, and an annular seal member 50. Hereinafter, one axial end (upper end in FIG. 7) of the barrel 31 is referred to as a “first end”, and the other axial end (lower end in FIG. 7) of the barrel 31 is “second”. The end. The trunk portion 31 opens at the first end and has a bottom wall 31a at the second end. The flange 32 is provided at the opening edge of the body part 31, the mandrel 40 is accommodated in the body part 31, and the seal member 50 is fitted to the outer peripheral surface of the body part 31. The trunk portion 31 and the flange 32 are made of aluminum, and are integrally formed by press molding.

Inside the barrel portion 31, an accommodating portion 31 d having a larger diameter than the large diameter portion 41 of the mandrel 40 is formed on the second end side, that is, the lower side of FIG. 7. Further, a communication portion 31 e that is connected to the housing portion 31 d and has a smaller diameter than the large-diameter portion 41 is formed inside the trunk portion 31. Further, in the body portion 31, an insertion portion 31f is formed on the first end side with respect to the communication portion 31e, that is, on the upper side in FIG.

The flange 32 has an annular protrusion 32 b, and the annular protrusion 32 b protrudes downward from the lower surface 32 a of the flange 32 and surrounds the body portion 31.
The mandrel 40 includes a rod-shaped operation part 42, a large diameter part 41 having a larger diameter than the operation part 42, and a fragile part 43 having a smaller diameter than the operation part 42. The fragile portion 43 is provided at the boundary between the operation portion 42 and the large diameter portion 41. The mandrel 40 is made of, for example, stainless steel. In a state where the mandrel 40 is accommodated in the body portion 31, the large diameter portion 41 is accommodated in the accommodation portion 31d, and the fragile portion 43 is accommodated in the communication portion 31e. Further, the operation part 42 is accommodated in the insertion part 31 f, and the tip of the operation part 42 protrudes from the trunk part 31. The mandrel 40 has a hardness greater than that of the body 31.

The seal member 50 is made of, for example, resin or rubber, and the inner peripheral portion 51 of the seal member 50 is circular. The inner peripheral portion 51 of the seal member 50 has an inner diameter that is slightly smaller than the outer diameter of the body portion 31. When the seal member 50 is fitted into the body portion 31, the inner peripheral portion 51 of the seal member 50 is compressed in the thickness direction (the axial direction of the body portion 31) and the diameter of the inner peripheral portion 51 is expanded. It deforms as follows.

The rivet member 30 is inserted into the liquid injection hole 14 c after the lid body 14 is joined to the opening 13 a of the case body 13.
Next, the rivet member 30 inserted into the liquid injection hole 14c will be described.

As shown in FIG. 8, when the rivet member 30 is inserted into the liquid injection hole 14 c from the bottom wall 31 a of the body portion 31, the bottom wall 31 a of the body portion 31 is positioned in the case 11 and the flange 32 is outside the case 11. The rivet member 30 is fastened to the lid body 14 so as to be positioned at the position. That is, the operation part 42 of the mandrel 40 is separated from the large diameter part 41 with the fragile part 43 as a boundary, and is removed from the body part 31. As a result of the operation of removing the operation portion 42 from the body portion 31, the large-diameter portion 41 of the mandrel 40 is press-fitted into the body portion 31 to expand the diameter of the body portion 31, so that the caulking portion 34 is formed in the body portion 31. The The outer peripheral surface of the caulking portion 34 is in close contact with the periphery of the liquid injection hole 14 c on the back surface 14 b of the lid body 14 and seals the liquid injection hole 14 c.

When the rivet member 30 is inserted into the liquid injection hole 14c, the upper surface 50a of the seal member 50 faces the lower surface 32a of the flange 32, and the lower surface 50b of the seal member 50 faces the surface 14a of the lid body 14.

The rivet member 30 is fastened to the lid body 14 by the caulking portion 34 and the flange 32, and the seal member 50 is sandwiched between the lower surface 32a of the flange 32 and the surface 14a of the lid body 14. The axial force accompanying the fastening acts on the seal member 50 via the lower surface 32a of the flange 32 and the annular protrusion 32b, and the seal member 50 is compressed in the axial direction.

When the lower surface 32a of the flange 32 and the annular protrusion 32b are in close contact with the upper surface 50a of the seal member 50, a predetermined surface pressure is generated between the lower surface 32a of the flange 32 and the upper surface 50a of the seal member 50. Similarly, when the lower surface 50 b of the seal member 50 is in close contact with the surface 14 a of the lid body 14, a predetermined surface pressure is generated between the lower surface 50 b of the seal member 50 and the surface 14 a of the lid body 14. The liquid injection hole 14c is sealed outside the case 11 by the seal member 50 in which surface pressure is generated on the upper surface 50a and the lower surface 50b.

Thus, in a state where the liquid injection hole 14 c is sealed by the rivet member 30, the caulking portion 34 located in the case 11 of the rivet member 30 is not in contact with the inner surface of the case main body 13. Further, the sealing member 50 of the rivet member 30 is located on the lid body 14 so that the whole does not protrude from the lid body 14.

As shown in FIG. 4, in the rivet member 30 of the present embodiment, a region of the rivet member 30 that contacts the surface 14 a of the lid body 14, that is, a region surrounded by the outer peripheral edge 50 d of the seal member 50 (hereinafter simply “ The region of the sealing member 50 is referred to as a center line L1 passing through the center in the short direction of the lid 14 and a center line L2 passing through the center in the longitudinal direction of the lid 14.

As shown in FIG. 6, the flange 32 and the seal member 50 of the rivet member 30 overlap with the pressure release valve 18 when viewed from the longitudinal direction of the lid body 14.
Next, the operation of the secondary battery 10 will be described.

In the secondary battery 10, when the case 11 is deformed by the internal pressure, the curvature of deformation on the center line L 1 is the largest (the radius of curvature is smallest) in the short direction of the lid 14, and the longitudinal direction of the lid 14 The curvature of deformation on the center line L2 is the largest (the radius of curvature is the smallest). That is, the curvature of deformation of the lid body 14 is the largest at the center portion including the center point C1 of the lid body 14 that is the intersection of the center line L1 and the center line L2 (the curvature radius of deformation of the lid body 14 is the smallest).

In the present embodiment, the center point C2 of the liquid injection hole 14c is shifted from the center point C1 of the lid body 14. That is, the liquid injection hole 14c is positioned at a position deviating from the position where the curvature of deformation of the lid body 14 is the largest.

In the case where the center point C2 of the liquid injection hole 14c is simply shifted from both the center line L1 passing through the center in the short direction of the lid body 14 and the center line L2 passing through the center in the longitudinal direction of the lid body 14, A part of the opening region 14c may be located on the center line L1 or the center line L2.

Therefore, in this embodiment, the opening region of the liquid injection hole 14c including the center point C2 is deviated from both the center line L1 and the center line L2. For this reason, the whole opening area | region of the liquid injection hole 14c can be located in the position which remove | deviated from the position where the curvature of deformation in the cover body 14 is the largest.

Further, when the center point C2 and the opening region of the liquid injection hole 14c are simply shifted from both the center line L1 and the center line L2, the region of the seal member 50 that is a region of the rivet member 30 that is in contact with the lid 14 is determined. A part may be located on the center line L1 or the center line L2.

Therefore, in this embodiment, the region of the seal member 50 is deviated from both the center line L1 and the center line L2. For this reason, the whole area | region of the sealing member 50 can be located in the position which remove | deviated from the position where the curvature of a deformation | transformation in the cover body 14 is the largest.

Therefore, according to the first embodiment, the following effects can be obtained.
(1) Since the center point C2 of the liquid injection hole 14c is located at a position shifted from the center point C1 having the largest curvature of deformation in the lid body 14, the rivet member 30 and the lid body 14 are deformed along with the deformation of the case 11. It can suppress that a clearance gap arises between.

(2) In the case where the lid body 14 has a rectangular shape as in the present embodiment, the distance from the center line L1 passing through the center in the short side direction of the lid body 14 to the end in the short side direction of the lid body 14 is The distance from the center line L2 passing through the center in the longitudinal direction of the lid body 14 to the longitudinal end of the lid body 14 is short. That is, the curvature (curvature radius) of deformation on the center line L1 is larger in the short direction of the lid body 14 than in the longitudinal direction of the lid body 14. In the present embodiment, the curvature of deformation of the lid body 14 around the liquid injection hole 14c can be reduced by shifting the center point C2 of the liquid injection hole 14c from the center line L1. Accordingly, it is possible to suitably suppress the occurrence of a gap between the rivet member 30 and the lid body 14 with the deformation of the case 11.

(3) The center point C2 of the liquid injection hole 14c, the opening area of the liquid injection hole 14c, and the area of the seal member 50 of the rivet member 30 are located at positions shifted from both the center line L1 and the center line L2. Yes. For this reason, the curvature of deformation of the lid body 14 around the liquid injection hole 14c can be further reduced. Accordingly, it is possible to suitably suppress the occurrence of a gap between the rivet member 30 and the lid body 14 with the deformation of the case 11.

(4) In order to suitably impregnate the electrolyte between the

electrodes

21 and 25 of the electrode assembly 12, it is preferable to position the liquid injection hole 14c as close to the center point C1 of the lid 14 as possible. According to the present embodiment, the liquid injection hole 14c is positioned between the protruding position of the positive electrode tab 24 and the protruding position of the negative electrode tab 28 in the electrode assembly 12, that is, at a position close to the center point C1 of the lid body 14. ing. For this reason, impregnation of the electrolyte solution between the

electrodes

21 and 25 of the electrode assembly 12 through the liquid injection hole 14c can be suitably performed.

(5) In order to suitably impregnate the electrolyte solution between the

electrodes

21 and 25 of the electrode assembly 12, it is particularly preferable that the liquid injection hole 14c be positioned as close as possible to the center line L1. According to the present embodiment, since the liquid injection hole 14c is positioned so as to overlap the pressure release valve 18 when viewed from the longitudinal direction of the lid body 14, the liquid injection hole 14c is positioned at a position close to the center line L1. be able to. For this reason, impregnation of the electrolyte solution between the

electrodes

(Second Embodiment)
Next, a second embodiment of the power storage device will be described with reference to FIGS. In the second embodiment, detailed description of the same parts as those in the first embodiment is omitted.

As shown in FIG. 10, a positive electrode conductive member 44 made of aluminum is electrically connected to the positive electrode tab 24. The positive electrode terminal 15 is welded to the positive electrode conductive member 44. A copper negative electrode conductive member 45 is electrically connected to the negative electrode tab 28. The negative electrode terminal 16 is welded to the negative electrode conductive member 45.

Each of the

conductive members

44 and 45 includes rectangular plate-like tab

joint portions

44a and 45a,

curved portions

44b and 45b curved in a crank shape, and rectangular plate-like terminal

joint portions

44c and 45c. The

curved portions

44b and 45b are continuous with the corresponding tab

joint portions

44a and 45a, and the terminal

joint portions

44c and 45c are continuous with the corresponding

curved portions

44b and 45b.

The positive electrode terminal 15 is bonded to the terminal bonding portion 44 c of the positive electrode conductive member 44. The negative electrode terminal 16 is bonded to the terminal bonding portion 45 c of the negative electrode conductive member 45. Therefore, the positive electrode tab 24 and the positive electrode terminal 15 are arranged side by side in the longitudinal direction of the lid body 14, and the negative electrode tab 28 and the negative electrode terminal 16 are arranged side by side in the longitudinal direction of the lid body 14. Further, the tab

joint portions

44a and 45a are brought closer to the lid body 14 than the terminal

joint portions

44c and 45c by the

curved portions

44b and 45b. Therefore, in the second embodiment, the length of the shortest distance between the lid body 14 and the electrode assembly 12 is shorter than that in the first embodiment due to the presence of the

curved portions

44b and 45b. Yes.

That is, as shown in FIG. 11, the upper end (upper surface) 12c of the electrode assembly 12 in the second embodiment is closer to the lid body 14 than in the first embodiment. Therefore, assuming a case 11 having the same size as the case 11 of the first embodiment, in the second embodiment, the electrode assembly 12 is larger than the first embodiment, and the energy density of the secondary battery 10 is the first. 1 higher than that of the first embodiment.

9 to 11, the liquid injection hole 14c and the pressure release valve 18 are located between the positive electrode terminal 15 and the negative electrode terminal 16 in the longitudinal direction of the lid body 14. Furthermore, the liquid injection hole 14c and the pressure release valve 18 are positioned between the positive electrode tab joint 44a (or the positive electrode tab 24) and the negative electrode tab joint 45a (or the negative electrode tab 28). Therefore, the liquid injection hole 14 c and the pressure release valve 18 are gathered and arranged at the center in the longitudinal direction of the lid body 14. The central portion of the lid body 14 is a portion including the center point C 1 in the lid body 14, and is located between the protruding position of the positive electrode tab 24 and the protruding position of the negative electrode tab 28 in the longitudinal direction of the lid body 14.

Specifically, the pressure release valve 18 is located on the center line L1 passing through the center in the short direction of the lid body 14 in the center portion of the lid body 14 and the center passing through the center in the longitudinal direction of the lid body 14. It is located closer to the positive electrode tab 24 than the line L2.

The liquid injection hole 14 c is located in a position closer to one long side of the lid body 14 than the center line L 1 in the central portion of the lid body 14. The liquid injection hole 14 c does not overlap the pressure release valve 18 when viewed from the longitudinal direction of the lid body 14, and is disposed at a position close to one long side of the lid body 14. In addition, the liquid injection hole 14 c does not overlap with the pressure release valve 18 when viewed from the short side direction of the lid body 14 and is located away from the pressure release valve 18 in the longitudinal direction. More specifically, the center point C2 of the liquid injection hole 14c, the opening area of the liquid injection hole 14c, and the area of the seal member 50 of the rivet member 30 are the longitudinal direction of the cover body 14 in the central portion of the cover body 14. At a position away from the pressure relief valve 18.

As in the first embodiment, the center point C2 of the liquid injection hole 14c, the opening area of the liquid injection hole 14c, and the area of the seal member 50 of the rivet member 30 are deviated from both the center line L1 and the center line L2. It is located at the position.

Thus, when the liquid injection hole 14c is located at the center of the lid body 14, the electrolytic solution is impregnated when the electrolyte is impregnated between the

electrodes

21 and 25 of the electrode assembly 12 via the liquid injection hole 14c. The positive electrode tab 24 and the tab joint portion 44a or the negative electrode tab 28 and the tab joint portion 45a are not obstructed, and the impregnation with the electrolyte can be suitably performed. The central portion of the lid body 14 is a portion that is more easily deformed when the pressure is increased than the long side edge portion and the short side edge portion of the lid body 14. Therefore, when the pressure release valve 18 is in the center portion of the lid body 14, when the pressure rises, the periphery of the pressure release valve 18 is deformed in substantially the same manner, and the pressure release valve 18 is stabilized with a predetermined release pressure. Can be cleaved. In addition, when the pressure release valve 18 is located at the center of the lid body 14, when the pressure in the case 11 rises, the positive electrode tab 24 and the tab joint 44a, and the negative electrode tab 28 and the tab joint 45a The pressure release valve 18 is prevented from being covered from the inside of the case 11.

Therefore, in order to increase the energy density of the secondary battery 10, the positive electrode tab 24 and the positive electrode terminal 15 are arranged in the longitudinal direction of the lid body 14, and the negative electrode tab 28 and the negative electrode terminal 16 are arranged in the longitudinal direction of the lid body 14. In this case, it is preferable that the liquid injection hole 14 c and the pressure release valve 18 are gathered and arranged in the central portion of the lid body 14.

When the liquid injection hole 14 c and the pressure release valve 18 are collected and arranged at the center of the lid body 14, there is a possibility that the rivet member 30 sealing the liquid injection hole 14 c is arranged near the pressure release valve 18. There is.

However, a portion around the liquid injection hole 14c in the lid body 14 is sandwiched by the caulking portion 34 and the flange 32 of the rivet member 30, and deformation of the portion is suppressed by the sandwiching. Further, the degree of suppression of deformation differs around the liquid injection hole 14 c in the lid 14 depending on the caulking degree of the rivet member 30. Therefore, the lid body 14 includes a portion in which the deformation is suppressed by the rivet member 30 and a portion in which the deformation is not suppressed without being affected by the rivet member 30, and the portion in which the deformation is suppressed is also deformed. The degree of is different.

(6) Therefore, in the second embodiment, even if the liquid injection hole 14 c and the pressure release valve 18 are gathered at the center of the lid body 14, the liquid injection hole 14 c and the rivet member 30 are separated from the pressure release valve 18. The liquid injection hole 14 c and the rivet member 30 are arranged at positions where they do not overlap the pressure release valve 18 when viewed from the short side direction and the long side direction of the lid body 14. Therefore, a portion where deformation is not suppressed is located around the pressure release valve 18 in the lid body 14, and a portion where deformation is suppressed by the rivet member 30 is not located. In other words, the portion where the deformation is not suppressed and the portion where the deformation is suppressed do not coexist around the pressure release valve 18 in the lid body 14. Therefore, when the pressure in the case 11 reaches the opening pressure, the degree of deformation due to the pressure does not vary around the pressure releasing valve 18 in the lid body 14, and the pressure releasing valve 18 is suitably cleaved over the entire circumference. Can be made. That is, the pressure release valve 18 can be cleaved with a predetermined opening pressure.

(7) In the secondary battery 10 of the second embodiment, the pressure release valve 18 and the positive electrode tab 24 between the protruding position (tab joint portion 44a) and the protruding position of the negative electrode tab 28 (tab joint portion 45a) The injection holes 14c were collected and arranged. Therefore, the electrolyte solution can be preferably impregnated between the

electrodes

21 and 25 of the electrode assembly 12 through the liquid injection hole 14c, and the pressure release valve 18 is suitably cleaved at a predetermined opening pressure. be able to.

(8) The rivet member 30 was adopted as a member for sealing the liquid injection hole 14c. The rivet member 30 can be easily assembled. Further, the sealing operation of the liquid injection hole 14c is easier than the case where a female screw is provided on the inner peripheral surface of the liquid injection hole 14c and the bolt member is screwed into the female screw to seal the liquid injection hole 14c. . In the secondary battery 10 employing the rivet member 30, the positional relationship between the liquid injection hole 14 c and the pressure release valve 18 is regulated so that the influence of caulking of the rivet member 30 does not affect the pressure release valve 18. The release valve 18 can be stably cleaved.

In addition, you may change the said embodiment as follows.
In the first embodiment, the liquid injection hole 14 c may be positioned so as not to overlap the pressure release valve 18 when viewed from the longitudinal direction of the lid body 14. That is, if the deformation amount of the lid 14 around the liquid injection hole 14c is within a range that does not impair the sealing performance of the liquid injection hole 14c by the rivet member 30, the liquid injection hole 14c and the rivet The positional relationship of the members 30 can be freely changed.

In each of the above embodiments, the pressure release valve 18 may be at a position shifted from the center line L1.
In each of the above embodiments, the side wall or the bottom wall of the case body 13 may be a case wall provided with the pressure release valve 18.

In the first embodiment, the liquid injection hole 14 c may be positioned in a region other than the region between the protruding position of the positive electrode tab 24 and the protruding position of the negative electrode tab 28 in the electrode assembly 12.
In the second embodiment, the liquid injection hole 14 c and the pressure release valve 18 may be positioned in a region other than the region between the protruding position of the positive electrode tab 24 and the protruding position of the negative electrode tab 28.

○ In each of the above embodiments, the region of the sealing member 50 of the rivet member 30 is other than the position shifted from both the center line L1 passing through the center in the short direction of the lid 14 and the center line L2 passing through the center in the longitudinal direction. It may be provided in the position. For example, the region of the seal member 50 of the rivet member 30 may be provided so as to be shifted from one of the center line L1 and the center line L2 and on the other center line. Further, a part of the region of the seal member 50 of the rivet member 30 may be provided so as to be located on the center point C1 of the lid body 14.

In the above embodiments, the opening region of the liquid injection hole 14c may be provided at a position other than the position shifted from both the center line L1 and the center line L2. For example, the opening region of the liquid injection hole 14c may be provided so as to be shifted from one of the center line L1 and the center line L2 and on the other center line. Furthermore, a part of the opening region of the liquid injection hole 14 c may be provided so as to be located on the center point C 1 of the lid body 14.

In each of the above embodiments, the center point C2 of the liquid injection hole 14c may be provided so as to be shifted from one of the center line L1 and the center line L2 and on the other center line.
(Circle) in each said embodiment, you may abbreviate | omit the annular convex part 32b. Further, instead of the annular protrusion 32b, the lid 14 may be provided with a protrusion protruding from the surface 14a toward the seal member 50. Moreover, you may provide both the cyclic | annular convex part 32b and the convex part of the cover body 14. FIG.

In the above embodiments, the side wall or the bottom wall of the case body 13 may be a case wall provided with the liquid injection hole 14c.
In each embodiment described above, a member other than the rivet member 30 such as a bolt member may be employed as the sealing member. In the case where the liquid injection hole 14c is sealed by the sealing member before the lid 14 is joined to the opening 13a of the case body 13, the sealing member in the sealing member is affected by the welding heat accompanying the joining. It is preferable to position the liquid injection hole and the sealing member at a position away from the end of the lid body 14 so as to be suppressed.

As the positive electrode metal foil 22, a foil made of a metal other than aluminum may be adopted.
As the negative electrode metal foil 26, a foil made of a metal other than copper may be adopted.
○ Only one side of the positive electrode 21 may have the positive electrode active material layer 23.

○ Only one surface of the negative electrode 25 may have the negative electrode active material layer 27.
The electrode assembly 12 may be a wound type.
The secondary battery 10 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 shape of the case 11 may be changed. For example, the case may have a square shape with a square case wall, or may have a cylindrical shape.
The present invention may be applied to a power storage device such as an electric double layer capacitor.

Claims

A plurality of positive electrodes provided with a positive electrode active material layer, a plurality of negative electrodes provided with a negative electrode active material layer, and a plurality of separators, wherein the positive electrodes and the negative electrodes are alternately stacked with the separator interposed therebetween. An electrode assembly;
A case comprising a case wall and containing the electrode assembly and the electrolyte therein;
A liquid injection hole penetrating the case wall;
A sealing member for sealing the liquid injection hole,
A power storage device in which a center point of the liquid injection hole and a center point of the case wall are shifted from each other.
The power storage device according to claim 1, wherein the liquid injection hole has an opening region that is shifted from a center point of the case wall.
3. The power storage device according to claim 1, wherein a region of a portion of the sealing member that contacts the case wall is deviated from a center point of the case wall.
The positive electrode and the negative electrode each have a positive electrode tab and a negative electrode tab in a shape protruding from their edges,
The power storage device according to any one of claims 1 to 3, wherein the liquid injection hole is located between a protruding position of the positive electrode tab and a protruding position of the negative electrode tab in the electrode assembly. .
The case wall includes a pressure release valve for releasing the pressure in the case to the outside of the case;
The power storage device according to claim 4, wherein the pressure release valve is located between a protruding position of the positive electrode tab and a protruding position of the negative electrode tab.
The case wall is rectangular;
The power storage device according to any one of claims 1 to 5, wherein a center point of the liquid injection hole is located at a position shifted from a center line passing through a center in a short direction of the case wall.
The center point of the liquid injection hole is located at a position deviated from both a center line passing through the center in the short direction of the case wall and a center line passing through the center in the longitudinal direction of the case wall. Power storage device.
The pressure relief valve is located on a center line passing through the center in the short direction of the case wall;
The power storage device according to claim 5, wherein the liquid injection hole overlaps the pressure release valve when viewed from a longitudinal direction of the case wall.
The case wall includes a pressure release valve for releasing the pressure in the case to the outside of the case, and the pressure release valve is located on a center line passing through a center in a short direction of the case wall,
The power storage device according to claim 6 or 7, wherein the liquid injection hole overlaps with the pressure release valve as viewed from a longitudinal direction of the case wall.
10. The power storage device according to claim 5, wherein the liquid injection hole does not overlap the pressure release valve when viewed from the short side direction of the case wall.
The power storage device according to claim 10, wherein the sealing member is a rivet member.
The power storage device according to any one of claims 1 to 11, wherein the power storage device is a secondary battery.