JP2016051597A - Sealing structure for hermetically sealed type power storage device, hermetically sealed type power storage device and manufacturing method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing structure for hermetically sealed type power storage device, a hermetically sealed type power storage device and a method of manufacturing the same that can also enhance the sealing performance of an injection hole under even a sealing state before welding.SOLUTION: A sealing port plate having a liquid injection hole and a sealing tap for sealing the liquid injection hole are provided. The sealing tap has a holding member and a press-fit member. The sealing port plate has a deep counterbore around the liquid injection hole on a surface at a side of the sealing port plate which is joined to the holding member. The press-fit member has a base portion joined to the holding member and a projection portion inserted in the liquid injection hole. The base portion has a predetermined diameter dimension. The projection portion has a first side surface portion at the base portion side and a second side surface portion at the tip side. A part of the first side surface portion and the inner peripheral surface of the liquid injection hole are brought into contact with each other over the whole periphery of the inner peripheral surface. The intersection angle θ1 between the contact portion and the direction vertical to the principal surface of the holding member under an unloaded condition is equal to a predetermined value, the diameter PD1 of the boundary between the projection portion and the base portion, the diameter PD3 at the tip and the diameter HD1, the maximum diameter PD5 of the second side surface portion and the diameter HD1, and the diameter PD2 of the boundary between the first side surface portion and the second side surface portion and the diameter PD5 respectively satisfy predetermined dimensional relationships, and a gap L1 is provided between the base portion and the bottom portion of the deep counterbore portion.SELECTED DRAWING: Figure 4A

Description

  The present invention relates to a sealing structure provided in a sealed electric storage device, and particularly to a sealing structure that seals a liquid injection hole provided in a sealing plate that seals an opening of a case with a sealing plug.

  In recent years, as sealed power storage devices used for mobile devices such as mobile phones, portable AV devices, and notebook computers, and various power sources such as stationary devices and mobile devices, capacitors such as lithium ion capacitors and electric double layer capacitors, nickel- Secondary batteries such as alkaline storage batteries such as hydrogen storage batteries and nickel-cadmium storage batteries and lithium ion batteries are widely used. In a sealed electric storage device, a power generation element in which an electrode group consisting of a positive electrode and a negative electrode is impregnated with an electrolyte is housed in a case made of a metal plate. The electrolyte may be injected from the liquid injection hole with a nozzle or the like after the electrode group is accommodated in the case and welded between the sealing plate and the case opening. This is because the sealing failure caused by the electrolyte adhering to the welded portion is suppressed because the gap between the sealing plate and the case opening is welded with the electrolyte still not in the case. In this case, the liquid injection hole is closed by a sealing plug formed of an elastic material such as rubber after the electrolyte is injected into the case (Patent Document 1, etc.).

  Usually, leakage inspection by sampling is performed on a sealed electric storage device. This is because if the sealing type power storage device has a sealing failure, the electrolyte leaks and damages the devices arranged around the power storage device, or the performance of the power storage device decreases.

  In the leak inspection, the sealing plate and the outer can are welded, and an electrolyte is injected from the injection hole, and then helium gas is injected from the injection hole. Next, a sealing plug having a metal holding member is inserted into the liquid injection hole, and the metal portion of the sealing plug and the sealing plate are welded to complete the sealed electric storage device. Finally, this sealed electricity storage device is installed in a decompression chamber and the helium concentration in the decompression chamber is measured (Patent Documents 2 and 3, etc.).

JP 2000-268811 A JP 2002-117901 A JP 2014-35830 A

  It is difficult to seal the case by simply inserting a conventional sealing plug into the liquid injection hole. For this reason, helium gas that has been press-fitted for leak inspection is inserted into the injection hole (hereinafter referred to as the inserted state) and then welded to the metal part and the sealing plate (hereinafter referred to as sealing). Until it gets out of the case. That is, even if helium gas is injected, the internal pressure of the case at the time of leak inspection is reduced to almost the same as the atmospheric pressure. Even if the pressure in the decompression chamber is reduced and the pressure difference between the inside and the outside of the case is increased, the degree is limited and it is difficult to detect a minute sealing failure. Under the present situation where higher power storage device performance is required, it is desired to perform a leakage inspection under conditions that can detect even such a minute sealing failure.

  1st aspect of this invention is a sealing structure which seals the liquid injection hole which injects electrolyte to a sealing type electrical storage device, Comprising: The said sealing structure is a sealing board which has the said liquid injection hole, A sealing plug that seals the liquid injection hole, and the sealing plug includes a plate-shaped holding member that is bonded to the sealing plate, and a press-fit member that includes an elastic material and is bonded to the holding member. The sealing plate has a deep counterbore around the liquid injection hole on the surface to be joined to the holding member, and the liquid injection hole is a flat surface on the bottom side of the deep counterbore part. From the first opening on the top to the second opening on the plane on the side where the deep spot facing portion of the sealing plate is not formed, the sealing plate penetrates in the thickness direction, The press-fitting member includes a base that is joined to the holding member, and a protrusion that is provided so as to protrude from the base and is inserted into the liquid injection hole. The base has a diameter BD and a diameter HD1 of the first opening satisfying a relationship of diameter BD> diameter HD1, and the protruding portion is more base than the second opening in the sealed state. A first side surface portion on the side and a second side surface portion on the tip side with respect to the second opening, and a part of the first side surface portion and the inner peripheral surface of the liquid injection hole are the inner peripheral surface. The angle θ1 formed between the abutting portion and the direction perpendicular to the main surface of the holding member in an unloaded state is 0 ° or more and 45 ° or less, The diameter PD1 at the boundary of the protrusion with the base, the diameter PD3 at the tip, and the diameter HD1 satisfy the relationship of diameter PD1> diameter HD1> diameter PD3, and the maximum in the second side surface portion of the protrusion The diameter PD5 and the diameter HD1 satisfy the relationship of diameter PD5> diameter HD1, and the protrusion of the protrusion The diameter PD2 at the boundary between the one side surface portion and the second side surface portion and the diameter PD5 satisfy the relationship of diameter PD5> diameter PD2, and there is a gap between the base portion and the bottom portion of the deep spot facing portion. The present invention relates to a sealed structure for a sealed electric storage device provided with L1.

  A second aspect of the present invention includes a case including the sealing structure, a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte, which are accommodated in the case. The present invention relates to a sealed electric storage device.

  A third aspect of the present invention is a method for manufacturing a sealed electricity storage device including the above-described sealing structure, the step of preparing a bottomed outer can, the sealing plate, and the sealing plug; A step of accommodating the electrode group in the outer can, a step of welding the opening end of the outer can in which the electrode group is accommodated, and a peripheral edge of the sealing plate, and impregnating the electrode group with an electrolyte. A step of injecting an inert gas from the injection hole of the sealing plate welded to the outer can, and a state in which the interior of the outer can is pressurized by the injected inert gas. The step of press-fitting the press-fitting member into the liquid injection hole, the step of welding the sealing plate and the sealing plug together with the press-fitting member press-fitted into the liquid injection hole, and the sealing Measuring the amount of inert gas leaking from the electricity storage device. The method of manufacturing a mold storage device.

  According to the present invention, at the stage where the sealing plug is inserted into the liquid injection hole (inserted state), the hermeticity of the electricity storage device pressurized with helium gas or the like is improved, so the leakage inspection is performed under more strict conditions. be able to. Therefore, even a minute sealing failure can be detected, and the long-term reliability of the sealed electric storage device is improved.

1 is a perspective view of a square sealed electric storage device to which a sealing structure according to an embodiment of the present invention is applied. 1 is a longitudinal sectional view schematically showing an electricity storage device according to an embodiment of the present invention. It is sectional drawing which shows a part of sealing plate which concerns on 1st Embodiment of this invention. It is sectional drawing which shows a part of sealing plate which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows a part of sealing plate which concerns on 3rd Embodiment of this invention. It is sectional drawing (a) and top view (b) which show the sealing stopper which concerns on 1st Embodiment of this invention. It is sectional drawing which shows the sealing stopper which concerns on 2nd Embodiment of this invention. It is a side view which shows an example of the sealing stopper which concerns on 1st Embodiment. It is a side view which shows another example of the sealing plug which concerns on 1st Embodiment. It is a side view which shows an example of the sealing stopper which concerns on 2nd Embodiment. It is a side view which shows another example of the sealing stopper which concerns on 2nd Embodiment. It is sectional drawing which shows an example of the liquid injection hole vicinity of a sealing board in an insertion state. It is sectional drawing which shows an example of the liquid injection hole vicinity of a sealing board in a sealing state. It is sectional drawing which shows an example of the liquid injection hole vicinity of a sealing board in a sealing state. It is sectional drawing which shows another example of the liquid injection hole vicinity of a sealing board in a sealing state. It is an expanded sectional view in FIG. It is sectional drawing which shows another example of the liquid injection hole vicinity of a sealing board in a sealing state. It is explanatory drawing which shows the process a among the manufacturing methods of the electrical storage device which concerns on one Embodiment of this invention. It is explanatory drawing which shows the process b among the manufacturing methods of the electrical storage device which concerns on one Embodiment of this invention. It is explanatory drawing which shows the process c among the manufacturing methods of the electrical storage device which concerns on one Embodiment of this invention. It is explanatory drawing which shows the process d among the manufacturing methods of the electrical storage device which concerns on one Embodiment of this invention.

[Description of Embodiment of the Invention]
First, the contents of the embodiment of the present invention will be listed and described.
The present invention is (1) a sealing structure that seals a liquid injection hole for injecting an electrolyte into a sealed electric storage device, wherein the sealing structure includes a sealing plate having the liquid injection hole, A sealing plug that seals the liquid injection hole, and the sealing plug includes a plate-shaped holding member that is bonded to the sealing plate, and a press-fitting member that includes an elastic material and is bonded to the holding member. The sealing plate has a deep counterbore around the liquid injection hole on the surface to be joined to the holding member, and the liquid injection hole is on a plane on the bottom side of the deep counterbore. The press-fitting member penetrates the sealing plate in the thickness direction from a certain first opening to a second opening on a plane on the side where the deep spot facing portion of the sealing plate is not formed. Is provided with a base that is joined to the holding member, and a protrusion that is provided so as to protrude from the base and is inserted into the liquid injection hole. The base portion has a diameter BD and a diameter HD1 of the first opening satisfy a relationship of diameter BD> diameter HD1, and the protruding portion is closer to the base side than the second opening in a sealed state. A first side surface portion and a second side surface portion on a tip side of the second opening portion, wherein a part of the first side surface portion and an inner peripheral surface of the liquid injection hole are all of the inner peripheral surface. An angle θ1 between the abutting portion and a direction perpendicular to the main surface of the holding member in an unloaded state is 0 ° or more and 45 ° or less, and the projecting portion The diameter PD1 at the boundary with the base portion, the diameter PD3 at the tip, and the diameter HD1 satisfy the relationship of diameter PD1> diameter HD1> diameter PD3, and the maximum diameter PD5 at the second side surface portion of the projecting portion. And the diameter HD1 satisfies the relationship of diameter PD5> diameter HD1, and the first side of the protruding portion The diameter PD2 at the boundary between the portion and the second side surface portion and the diameter PD5 satisfy the relationship of diameter PD5> diameter PD2, and there is a gap L1 between the base portion and the bottom portion of the deep spot facing portion. The present invention relates to a sealed structure for a sealed electricity storage device. Thereby, even in the inserted state, the hermeticity of the electricity storage device pressurized by helium gas or the like is improved.

  (2) It is preferable that the said protrusion part is equipped with the hollow which goes to the said base part from the said front-end | tip. This is because it becomes easier to insert the protruding portion into the liquid injection hole.

  (3) The ratio HD1 / PD4 between the diameter HD1 and the diameter PD4 of the projecting portion in an unloaded state at the contacting portion is preferably 0.85 to 0.95. This is because the sealing performance in the inserted state is further improved.

  (4) The elastic material includes ethylene-propylene-diene rubber or fluororubber, and the ethylene-propylene-diene rubber is at least one selected from the group consisting of ethylidene norbornene, 1,4-hexadiene, and dicyclopentadiene. The durometer type A according to JIS K 6253 of the elastic material preferably has a hardness of 30 to 80. This is because the hermeticity of the electricity storage device is easily maintained over a long period of time.

  (5) It is preferable that the said 1st opening part of the said liquid injection hole has a chamfering part. This is because the sealing performance in the inserted state is further improved.

  In addition, the present invention includes (6) a case including the sealing structure, a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte, which are accommodated in the case. The present invention relates to a sealed electric storage device. This sealed electric storage device is excellent in sealing performance and has long-term reliability.

  (7) The sealed electric storage device may include an inert gas, and the pressure in the case may be greater than atmospheric pressure. According to the sealed electric storage device of the present invention, the effect of preventing the electrolyte from leaking is high even when such a high internal pressure is present.

  Furthermore, the present invention is (8) a method for manufacturing a sealed electricity storage device including the above-described sealing structure, the step of preparing a bottomed outer can, the sealing plate, and the sealing plug; A step of accommodating the electrode group in the outer can, a step of welding the opening end of the outer can in which the electrode group is accommodated, and a peripheral edge of the sealing plate, and impregnating the electrode group with an electrolyte. A step of injecting an inert gas from the injection hole of the sealing plate welded to the outer can, and a state in which the interior of the outer can is pressurized by the injected inert gas. The step of press-fitting the press-fitting member into the liquid injection hole, the step of welding the sealing plate and the sealing plug together with the press-fitting member press-fitted into the liquid injection hole, and the sealing Measuring the amount of inert gas leaking from the electricity storage device. A method for manufacturing a closed-type power storage device. The sealed electric storage device manufactured by this method has excellent sealing properties and long-term reliability.

  The sealing structure of the present invention is a sealing structure that seals a liquid injection hole for injecting an electrolyte into a sealed electric storage device. The sealing structure includes a sealing plate having a liquid injection hole and a sealing plug for sealing the liquid injection hole. For example, as shown in FIG. 1, an outer can 12, an opening of the outer can 12, a sealing plate 13 having an electrolyte injection hole, and a sealing plug 11 that seals the injection hole are provided. ing. In addition, in FIG. 1, the state by which the sealing stopper 11 is inserted in the liquid injection hole is shown.

First, the shapes of the liquid injection hole and the sealing plug will be briefly described with reference to FIGS. 3A and 4A. Details of each will be described later.
For example, as shown in FIG. 3A, the sealing plate 13 includes a liquid injection hole 20 penetrating the sealing plate 13 in the thickness direction from the first opening 20a to the second opening 20b. Further, the sealing plate 13 is provided with a step for facilitating the injection of the electrolyte around the first opening 20a of the liquid injection hole 20 and for accommodating a base 33 (see FIG. 4A) of the press-fitting member 32 described later. A deep counterbore 21 is formed. The first opening 20 a is an opening formed inside the circumference that is the boundary between the liquid injection hole 20 and the deep spot facing portion 21, and is on the same plane as the bottom portion 21 </ b> B of the deep spot facing portion 21. It is in. The second opening 20b is an opening formed inside the circumference that is the boundary between the liquid injection hole 20 and the inside of the case, and the surface of the sealing plate 13 on which the deep countersink portion 21 is not formed. On the same plane.

  For example, as shown in FIG. 4A, the sealing plug 11 includes a plate-like holding member 31 joined to the sealing plate 13, and a press-fitting member 32 containing an elastic material and joined to the holding member 31. The press-fitting member 32 includes a base 33 that is joined to the holding member, and a protrusion 34 that is provided so as to protrude from the base 33 and is inserted into the liquid injection hole 20. Further, in the sealed state, the protruding portion 34 includes a first side surface portion 34a positioned on the base 33 side with respect to the second opening portion 20b, and a second side surface portion 34b positioned on the distal end side with respect to the second opening portion 20b. It has.

[Sealing plate]
The sealing plate 13 will be described with reference to FIGS. 3A to 3C.
(First embodiment)
The sealing plate 13 includes a liquid injection hole 20 that is a through hole and a deep spot facing portion 21. The depth L2 of the counterbore portion 21 is larger than the thickness L3 of the base portion 33 (L2> L3). A first opening 20a is formed in the approximate center of the bottom 21B of the counterbore 21.

  In FIG. 3A, the diameter of the inner peripheral surface 20c is the same HD1 in the first opening 20a and the second opening 20b, but gradually decreases in a tapered shape from the first opening 20a to the second opening 20b. It may be smaller.

(Second Embodiment)
In the present embodiment, at least one step is provided on the inner peripheral surface 20c of the liquid injection hole 20 so that the diameter of the inner peripheral surface 20c decreases stepwise from the first opening 20a toward the second opening 20b. A portion 20d is formed (see FIG. 3B). At this time, the shape and dimensions of the protruding portion 34 and the size of the inner peripheral surface 20c ′ are set so that the first side surface portion 34a and the inner peripheral surface 20c ′ of the stepped portion 20d are in contact with each other over the entire circumference. May be. Thereby, not only the vicinity of the 1st opening part 20a of the liquid injection hole 20 but the vicinity of the step part 20d can maintain airtightness.

  In FIG. 3B, one step 20d is formed at a position of depth H1 from the first opening 20a. The number of stepped portions 20d is not limited to one and may be two or more. The inner diameter (large hole diameter) of the liquid injection hole in the portion surrounded by the inner peripheral surface 20c is the diameter HD1 of the first opening 20a, and the inner diameter (smaller diameter) of the liquid injection hole in the portion surrounded by the inner peripheral surface 20c ′. (Hole diameter) is the diameter HD2 of the second opening 20b.

(Third embodiment)
In the present embodiment, the sealing plate 13 has a chamfered portion 20e in the vicinity of the first opening 20a (see FIG. 3C). When the protruding portion 34 is inserted into the liquid injection hole 20, the elastic material constituting the first side surface portion 34a is deformed and comes into contact with the chamfered portion 20e. Since the contact area between the first side surface portion 34a and the inner peripheral surface 20c is larger than the case where the chamfered portion 20e is not provided, the sealing performance is further improved. In the example of FIG. 3B, a chamfer similar to that of the example of FIG. 3C can be provided in the vicinity of the first opening 20a and / or in the vicinity of the stepped portion 20d.

  When the chamfered portion 20e is provided, the upper boundary of the chamfered portion 20e (intersection line between the chamfered portion 20e and the bottom 21B of the counterbore portion 21) is the first opening 20a, and the diameter of the liquid injection hole 20 Is slightly smaller than the diameter HD1 of the first opening 20a.

  The inclination angle of the chamfered portion 20e (the inclination of the counterbore portion 21 with respect to the bottom portion 21B) θ3 is the outer edge of the boundary portion between the protruding portion 34 (strictly, the first side surface portion 34a) and the base portion 33 in the sealed state. It is preferable to set according to the ratio L1 / X1 between the horizontal distance X1 and the vertical distance (L1) between the outer edge of the first opening 20a (see FIG. 9). In particular, when α = tan θ3 / (L1 / X1), it is preferable to set the angle θ3 so that 0.8 ≦ α ≦ 1.2. That the relationship between the angle θ3 and the ratio (L1 / X1) satisfies this range means that the outer edge of the projecting portion 34 compressed between the bottom portion 21B of the counterbore portion 21 and the base portion 33, the chamfered portion 20e, Is almost on a plane. Therefore, while increasing the contact pressure between the first side surface portion 34a and the first opening portion 20a, the repulsive force (acting in the direction of pushing up the base portion 33 and the holding member 31) generated by compressing the elastic material constituting the protruding portion 34. Force). Therefore, even if the pressure inside the case 10 is high, it becomes easier to achieve high sealing performance.

[Sealing stopper]
The sealing plug will be described with reference to FIGS. 4A and 4B.
(First embodiment)
The sealing plug 11 includes a plate-like holding member 31 and a press-fitting member 32. The diameter of the holding member 31 is larger than the bottom surface 21B of the deep spot facing portion 21 provided on the sealing plate 13 and larger than the first opening 20a. In the sealed state, the holding member 31 comes into contact with the surface of the sealing plate 13 including the deep spot facing portion 21 so as to cover the deep spot facing portion 21 (see FIG. 7 and the like). The holding member 31 is preferably formed of a metal plate. This is because the penetration of the electrolyte is suppressed and it is easier to prevent the electrolyte from leaking outside the electricity storage device.

  The press-fitting member 32 includes a base portion 33 and a protruding portion 34. The base 33 and the protrusion 34 can be obtained by integrally molding an elastic material. The boundary portion between the protruding portion 34 and the base portion 33 is, for example, a circle. The base 33 has a disk shape, for example.

  The diameter BD of the base 33 is larger than the diameter HD1 of the first opening (diameter BD> diameter HD1). The diameter PD1 of the boundary portion between the first side surface 34a and the base 33 is larger than the diameter HD1 of the first opening 20a, and the diameter PD3 at the tip is smaller than the diameter HD1 of the first opening 20a (diameter PD1> Diameter HD1> diameter PD3). As described above, when the diameter of the liquid injection hole 20 decreases from the first opening 20a toward the second opening 20b, the tip diameter PD3 is smaller than the diameter HD2 of the second opening 20b. When the boundary portion between the first side surface portion 34a and the base portion 33 includes a curved surface or the like, and the boundary portion is not clear, the first side surface portion 34a is held by the holding member 31 so as to include a portion having the largest curvature on the curved surface. The diameter of the cross section cut in the direction parallel to is the diameter PD1.

  Since the press-fitting member 32 has such a shape, the protruding portion 34 is not inserted into the liquid injection hole 20 up to the boundary portion with the base portion 33 and is locked to the first opening portion 20a by a part of the first side surface portion 34a. To do. Further, a part of the first side surface portion 34a and the inner peripheral surface 20c of the liquid injection hole 20 abut over the entire circumference of the inner peripheral surface 20c (hereinafter, the abutting portion is referred to as an abutting portion SH). . At least a part of the protrusion 34 is not engaged with the liquid injection hole 20. Therefore, in the sealed state, the projecting portion 34 includes a first side surface portion 34a positioned on the base 33 side with respect to the second opening portion 20b, and a second side surface portion 34b positioned on the distal end side with respect to the second opening portion 20b. (See FIG. 7).

  The maximum diameter PD5 of the second side surface portion 34b is larger than the diameter HD1 of the first opening 20a (diameter PD5> diameter HD1), and the diameter PD2 at the boundary between the first side surface portion 34a and the second side surface portion 34b is a diameter. It is smaller than PD5 (diameter PD5> diameter PD2). That is, the protrusion 34 is formed with a protrusion P formed by the second side surface portion 34b.

  Since the first opening portion 20a contacts the first side surface portion 34a, the second side surface portion 34b including the protrusion P formed by the second side surface portion 34b is disposed inside the case with respect to the second opening portion 20b. . Therefore, even when the case has a high internal pressure, the contact between the first opening 20a and the first side surface 34a is maintained by the protrusion P. Furthermore, since the protrusion P and the sealing plate 13 in the vicinity of the second opening 20b can come into contact with each other, further improvement in sealing performance can be expected. If the boundary portion is not clear, such as the boundary portion between the first side surface portion 34a and the second side surface portion 34b includes a curved surface, the second side surface portion 34b is included so as to include the portion with the largest curvature on the curved surface. The diameter of the cross section cut in the direction parallel to the holding member 31 is the diameter PD2.

  Conventionally, the sealing performance by the sealing plug is ensured mainly by welding the sealing plug and the sealing plate. Therefore, it is not a big problem that the sealing property before welding (insertion state) is not sufficient. However, as will be described later, when the leakage inspection is performed in a state where the internal pressure of the case is high, high sealing performance in the inserted state is required. Since this embodiment is provided with the above-described configuration, the sealing performance in the inserted state is further improved.

  Moreover, it can be said that having an excellent sealing property in the inserted state indicates that the power storage device is excellent in long-term reliability. Such an electricity storage device has a sealing property that can pass the leakage test even when the case has a high internal pressure. That is, it shows that it does not have a minute sealing defect, and the sealing performance over a long period can be ensured.

  The angle θ1 formed between the contact portion SH and the direction perpendicular to the main surface of the holding member 31 in an unloaded state is 0 ° or more and 45 ° or less (see FIG. 4A). In the present embodiment, the first side surface portion 34a includes the contact portion SH, and includes a tapered portion 34at having an angle θ1 of greater than 0 ° and 45 ° or less, and a straight portion 34as having an angle θ1 of 0 °. Have. In this case, the first side surface portion 34a is in contact with the first opening portion 20a and the inner peripheral surface 20c of the liquid injection hole 20 at the tapered portion 34at. The straight portion 34as may be in contact with the inner peripheral surface 20c of the liquid injection hole 20 or may not be in contact. The first side surface portion 34a is not limited to this shape, and may include only a tapered portion where the angle θ1 is greater than 0 ° and 45 ° or less, or includes only a straight portion where the angle θ1 is 0 °. May be.

  Further, the first side surface portion 34a may have a curved surface. In this case, an angle formed by taking a tangent line at a point on the curved surface and a plane including the tangent line and a direction perpendicular to the main surface of the holding member 31 can be regarded as the angle θ1.

  When the angle θ1 is within this range, a sufficient surface pressure can be obtained at the contact portion SH between the first side surface portion 34a and the first opening portion 20a, and high sealing performance in a sealed state before welding. Can be achieved. In particular, the angle θ1 is more preferably 5 ° or more, and further preferably 15 ° or more, in that the compressibility of the elastic material constituting the protruding portion 34 in the contact portion SH can be further increased. preferable. In addition, the angle θ1 is preferably 35 ° or less, and more preferably 30 ° or less. In addition, it is possible to adjust a surface pressure and a compressibility by adjusting the insertion depth to the injection hole 20 of the protrusion part 34. FIG.

  It is preferable that the ratio HD1 / PD4 of the minimum diameter PD4 of the protrusion 34 in the no-load state and the diameter HD1 of the first opening 20a in the contact portion SH is 0.85 to 0.95. By setting the relationship between the two diameters (HD1 and PD4) in this way, the compression ratio of the press-fitting member 32 at the contact portion SH, 1-HD1 / PD4, is in the range of 0.05 to 0.15. Thereby, the sealing property in the stage which inserted the press injection member 32 in the liquid injection hole 20 further improves.

  When at least one step portion 20d is formed on the inner peripheral surface 20c of the liquid injection hole 20, a part of the first side surface portion 34a and the inner peripheral surface 20c ′ of the step portion 20d You may contact | abut over (refer FIG. 10). In this case, the compression ratio (the value obtained by subtracting the inner diameter of the inner peripheral surface 20c ′ from the minimum diameter PD4) at the portion where the first side surface portion 34a and the inner peripheral surface 20c ′ of the stepped portion 20d contact each other is The position (H1) of the stepped portion and the inner circumference so that the compression ratio (1-HD1 / PD4) of the protruding portion 34 in the first opening 20a is approximately the same as that calculated by dividing by the small diameter PD4. The inner diameter of the surface 20c ′ may be set.

  The protrusion P by the second side surface portion 34b may be formed over the entire circumference on the distal end side of the projecting portion 34 (see FIG. 5A), or may be partially formed on the distal end side (see FIG. 5B). . In FIG. 5B, the protrusions P are formed at four locations on the protrusion 34. Here, the maximum diameter HD5 is the diameter of the maximum circle when a minimum virtual circle including the protrusion P is drawn in a direction parallel to the holding member 31. In addition, as will be described later, the diameter PD3 of the tip is the diameter when a minimum virtual circle including the entire tip portion is drawn when the tip of the protruding portion 34 has a hollow S therein.

  The maximum diameter PD5 is preferably about 1.05 to 1.2 times the diameter HD1 of the first opening 20a from the viewpoints of hermeticity and ease of insertion.

  The airtightness is ensured by the inner peripheral surface 20c of the liquid injection hole 20 and a part of the first side surface portion 34a contacting each other over the entire circumference of the inner peripheral surface 20c. Therefore, the protrusion P and the surface of the sealing plate 13 on which the second opening 20b is formed may not be in contact (see FIG. 7 and the like). Even in such a case, when the pressure inside the case 10 is very high, the sealing plug 11 is pushed up, and the protrusion P is pressed against the surface of the sealing plate 13 where the second opening 20b is formed. And the sealing performance is enhanced.

  It is preferable that the protrusion part 34 is provided with the hollow S which goes to the base part 33 from the front-end | tip (refer FIG. 4A). According to this embodiment, when the protrusion 34 is inserted into the liquid injection hole 20, the second side surface 34 b surrounding the hollow S can be deformed so as to be pushed into the hollow S. Therefore, it becomes easier to insert the protrusion 34 into the liquid injection hole 20.

  In FIG. 4A, the hollow S has a substantially cylindrical shape (strictly speaking, a shape spreading toward the tip from the base 33 side), but is not limited to this shape. For example, the hollow S may be formed in an I shape so as to penetrate the second side surface portion 34 b in a direction parallel to the holding member 31. The size and shape of the hollow S affects the ease of deformation and the repulsive force of the entire protrusion 34. Therefore, what is necessary is just to set the magnitude | size and shape of the hollow S suitably according to desired performance.

  The depth Ds of the hollow S is not particularly limited, but in particular, from the viewpoint of hermeticity, the depth Ds preferably does not extend from the end of the protruding portion 34 to the contact portion SH. Further, from the viewpoint of ease of insertion, the depth Ds preferably extends from the end of the protrusion 34 to the vicinity of the second opening 20b. The maximum cross-sectional area when the hollow S is cut in a direction parallel to the holding member 31 is not particularly limited. Especially, it is preferable that the said cross-sectional area is about 15 to 50% with respect to the area of the direction parallel to the holding member 31 at the front-end | tip of the protrusion part 34 from viewpoints, such as sealing property and ease of insertion.

  A gap L1 is formed between the base 33 and the bottom 21B of the counterbore 21 (see FIG. 7 and the like). When the protruding portion 34 is inserted into the liquid injection hole 20, the elastic material constituting the protruding portion 34 is pushed up by the first opening 20a and deforms, and the upper portion of the first opening 20a is bent. This bending of the elastic material acts in a direction in which the base 33 and the holding member 31 are pushed up, and lowers the sealing performance in the inserted state.

  The gap L <b> 1 accepts this bending and relaxes the action of the bending pushing up the base 33 and the holding member 31. Therefore, the insertion depth of the sealing plug 11 is maintained at a position close to the initial stage even before welding. Therefore, the sealing performance in the inserted state is improved. Further, since there is a gap L1 for receiving the deflection, even if the angle θ1 is 0 ° or more, the protrusion 34 is injected into the liquid injection hole 20 until the compression rate of the protrusion 34 by the liquid injection hole 20 reaches a desired value. It becomes easy to insert into.

  In consideration of maintaining the desired sealing performance over a long period of time, it is preferable to use ethylene-propylene-diene rubber (EPDM) or fluorine rubber as the elastic material contained in the press-fitting member. The ethylene-propylene-diene rubber preferably contains at least one selected from the group consisting of ethylidene norbornene, 1,4-hexadiene, and dicyclopentadiene. Especially, it is preferable that the diene component contains 3.0-10.5 mass%. The elastic material preferably has a durometer type A hardness of 30 to 80 in accordance with JIS K 6253.

  Examples of such a fluororubber include a rubbery copolymer (FEPM) of tetrafluoroethylene (TFE) and propylene, a rubbery copolymer (FKM) containing vinylidene fluoride (VDF) as a monomer unit, TFE and par A rubbery copolymer (FFKM) with fluoroalkyl vinyl ether can be exemplified. Examples of FKM include VDF-hexafluoropropylene (HFP) copolymer, VDF-pentafluoropropylene copolymer, VDF-trifluorochloroethylene copolymer, VDF-HFP-TFE copolymer, etc. It is rubbery.

  Furthermore, it is preferable that the heat resistance of the elastic material (safe use heat-resistant temperature that allows continuous use) is 90 ° C. or higher. The elastic material preferably has a compression set of 10% or less after being left for 1000 hours under the condition of environmental temperature: 100 ° C. The compression set can be measured by a compression set test based on JIS K6262, ASTM D395, or ISO815.

  FIG. 6A shows a state in which the sealing plug 11 is inserted into the liquid injection hole 20 formed in the sealing plate 13, and the peripheral portion of the holding member 31 and the front surface of the sealing plate 13 are joined by welding or the like. A state before insertion (inserted state) is shown in a sectional view. A gap G <b> 1 is generated between the sealing plate 13 and the holding member 31 due to the repulsive force of the elastic member constituting the protruding portion 32. However, even in this case, since the inner peripheral surface 20c of the liquid injection hole 20 and a part of the first side surface portion 34a are in contact with each other over the entire circumference of the inner peripheral surface 20c, the sealing performance is ensured. Is done.

  The protruding portion 34 is inserted from the liquid injection hole 20 into the case 10 from the portion separated by the distance L1 from the boundary portion with the base portion 33 to the tip thereof. A part of the first side surface portion 34a is in contact with the inner peripheral surface 20c including the first opening portion 20a of the liquid injection hole 20 to ensure hermeticity. At least a part of the second side surface portion 34 b and the tip end surface 34 c are not engaged with the liquid injection hole 20.

  The surface pressure of the contact portion SH is preferably 4.5 to 5.5 MPa at the maximum. This is because the sealing performance in the inserted state is further improved.

  The size of the gap L1 between the base portion 33 and the bottom portion 21B of the counterbore portion 21 depends on the diameter of the liquid injection hole 20, but is preferably 0.1 to 0.6 mm, for example. Thereby, it becomes easy to accept the bending of the elastic material which arises above the 1st opening part 20a, and the sealing performance in an insertion state further improves.

(Second Embodiment)
This embodiment is the same as the first embodiment except that the hollow S is not formed inside the protruding portion 34 (see FIG. 4B). The protrusion P may be formed over the entire circumference on the tip side of the protrusion (see FIG. 5C), or may be partially formed on the tip side (see FIG. 5D). In this case, from the viewpoint of ease of inserting the protruding portion 34 into the liquid injection hole 20, the angle θ2 formed by the second side surface portion 34b and the direction perpendicular to the main surface of the holding member 131 is equal to or larger than the angle θ1. It is preferable. As a result, the diameter PD3 of the tip is smaller than the diameter PD1 of the boundary portion and the diameter PD4 of the contact portion SH, so that the protruding portion 34 can be easily inserted into the liquid injection hole 20. This effect is particularly remarkable when the internal pressure of the case is high. Even when the hollow S is formed, the angle θ2 may be equal to or larger than the angle θ1. The angle θ2 is preferably larger than 5 ° and preferably smaller than 45 °.

[Power storage device]
The type of power storage device is not particularly limited. Examples include alkali metal ion capacitors such as lithium ion capacitors and sodium ion capacitors, and alkali metal ion secondary batteries such as lithium ion secondary batteries and sodium ion secondary batteries (hereinafter referred to as nonaqueous electrolyte secondary batteries). it can.

  A structure of an electricity storage device according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. However, the structure of the electricity storage device according to the present invention is not limited to the following structure. FIG. 2 is a longitudinal sectional view schematically showing a case where the electricity storage device 100 is cut by a cross-sectional line passing through the center line of the external negative electrode terminal 14 and cutting the long side of the electricity storage device 100.

  The electricity storage device 100 includes a stacked electrode group (see FIG. 2), an electrolyte (not shown), and a rectangular aluminum case 10 that accommodates these. The case 10 includes a bottomed outer can 12 having an upper opening, a sealing plate 13 that closes the upper opening, and a liquid filling plug 11. The sealing plate 13 and the liquid filling plug 11 have the above-described sealing structure. Make up body. The sealing structure includes at least a sealing plate 13, an inner peripheral surface 20 c and a first opening 20 a of the liquid injection hole 20 provided in the sealing plate 13, and the sealing plug 11.

  An external positive terminal 15 penetrating the sealing plate 13 is provided near one side of the sealing plate 13, and an external negative terminal 14 penetrating the sealing plate 13 is provided at a position near the other side of the sealing plate 13. Yes. Each terminal is preferably insulated from the case. A pressure control valve 17 is provided at a position near the external negative electrode terminal 14 of the sealing plate 13 to release the gas generated inside when the internal pressure of the electronic case 10 gradually increases. A liquid injection hole 20 (not shown) is provided at a position of the sealing plate 13 near the external positive terminal 15. The liquid injection hole 20, for example, inserts power generation elements (electrode group and electrolyte) into the container body 12, welds the sealing plate 13 to the opening of the container body 12, and then injects the electrolyte into the battery case 10. It is a hole for. The injection hole 20 is sealed with a sealing plug 11 shown in FIG. 4A and the like after the injection of the electrolyte into the case 10 is completed.

  The stacked electrode group is composed of a plurality of positive electrodes 2 and a plurality of negative electrodes 3 each having a rectangular sheet shape and a plurality of separators 1 interposed therebetween. The positive electrode, the negative electrode, and the separator will be described later. In FIG. 2, the separator 1 is formed in a bag shape so as to surround the positive electrode 2, but the form of the separator is not particularly limited. The plurality of positive electrodes 2 and the plurality of negative electrodes 3 are alternately arranged in the stacking direction within the electrode group.

  A positive electrode lead piece 2 c may be formed at one end of each positive electrode 2. The plurality of positive electrodes 2 are connected in parallel by bundling the positive electrode lead pieces 2 c of the plurality of positive electrodes 2 and connecting them to the external positive terminal 15 provided on the sealing plate 13 of the case 10. Similarly, a negative electrode lead piece 3 c may be formed at one end of each negative electrode 3. A plurality of negative electrodes 3 are connected in parallel by bundling the negative electrode lead pieces 3 c of the plurality of negative electrodes 3 and connecting them to the external negative terminal 14 provided on the sealing plate 13 of the case 10. It is desirable that the bundle of the positive electrode lead pieces 2c and the bundle of the negative electrode lead pieces 3c are arranged on the left and right sides of the one end surface of the electrode group with an interval so as to avoid mutual contact.

  Both the external positive terminal 15 and the external negative terminal 14 are columnar, and at least a portion exposed to the outside has a screw groove. A nut 4 is fitted in the screw groove of each terminal, and the nut 4 is fixed to the sealing plate 13 by rotating the nut 4. A flange portion 6 is provided in a portion of each terminal accommodated in the case, and the flange portion 6 is fixed to the inner surface of the sealing plate 13 via the washer 5 by the rotation of the nut 4.

  The case 10 may be increased by an inert gas such as helium gas so that the internal pressure is higher than atmospheric pressure (for example, when atmospheric pressure is 0 kPa (gauge pressure), higher than 0 kPa, preferably 100 kPa or less). Thus, even when the case 10 has a high internal pressure, according to the sealing structure of the present embodiment, high sealing performance can be achieved not only after welding but also in a sealed state before welding. it can. The inert gas is injected into the case 10 for leakage inspection and is not particularly limited. For example, helium gas, argon gas, nitrogen gas, etc. are mentioned.

  The injected inert gas usually escapes from the case 10 after the sealing plug 11 is inserted into the liquid injection hole 20 and before the holding member 31 and the sealing plate 13 are welded. For this reason, the internal pressure of the case 10 at the time of leakage inspection is reduced to substantially the same as the atmospheric pressure, and even if a leakage inspection is performed thereafter, it is difficult to detect a minute sealing failure. According to the sealing structure of the present embodiment, high sealing performance can be achieved in the insertion state before welding, and therefore, it can be subjected to a leakage inspection while the internal pressure of the case 10 is kept high. That is, since the leakage inspection can be performed under more severe conditions, the reliability is further increased.

  The leakage inspection is usually performed on a part of the manufactured electricity storage device. In general, for an electricity storage device that is not subjected to a leakage inspection, an inert gas is not injected into the case 10. Even in such a power storage device that is not injected with an inert gas, according to the present embodiment, it has a sealing property that can pass a leakage inspection performed under more severe conditions. , Sealing property over a long period (long-term reliability) is ensured.

[Method of manufacturing power storage device]
The electricity storage device can be manufactured as follows.
First, the outer can 12, the sealing plate 13, the sealing plug 11, and an electrode group described later are prepared. Next, the electrode group is accommodated in the outer can 12. Subsequently, the opening end of the outer can 12 and the peripheral edge of the sealing plate 13 are welded together to obtain the case 10 in which the electrode group is accommodated. After welding the outer can 12 and the sealing plate 13, an electrolyte is injected from the injection hole 20 provided in the sealing plate 13.

  Subsequently, the sealing plug 11 is inserted into the liquid injection hole 20 while applying a load. Finally, the holding member 31 of the sealing plug 11 and the sealing plate are welded to complete the electricity storage device. The method for welding the holding member 31 and the sealing plate 13 is not particularly limited, and for example, they can be joined by spot resistance welding. In spot resistance welding, a plurality of welds may be formed and joined around the first opening 20a on a circumference that is concentric with the first opening 20a. Moreover, you may form one continuous welding part in the circumference | surroundings of the 1st opening part 20a concentrically with this by laser welding. According to this embodiment, high sealing performance can be ensured in the inserted state. Therefore, the electrolyte can be prevented from leaking out of the electricity storage device through the liquid injection hole 20 even by partial joining such as spot resistance welding.

  On the other hand, an electricity storage device into which an inert gas used for leakage inspection is injected can be manufactured as follows. The preparation process of the outer can 12, the sealing plate 13, the sealing plug 11 and the electrode group, the electrode group accommodation process, the welding process between the outer can 12 and the sealing board 13 and the electrolyte impregnation process are performed in the same manner as described above. .

  When the outer can 12 and the sealing plate 13 are welded and the electrolyte is held inside the case 10, an inert gas is further injected into the case 10. The inert gas is injected by, for example, an inert gas injection device. Schematic diagrams of the inert gas injection device are shown in FIGS.

  The inert gas injection device 40 supports the vacuum pad 41 for fixing the sealing plug 11, the vacuum pad 41, for example, a cylinder 42 having a cylindrical shape, an O-ring 43 disposed at the tip of the cylinder 42, and the case 10. Are provided with an inert gas supply device 44 (inert gas cylinder) for supplying an inert gas, and a vacuum pump 45 A connected to the vacuum pad 41. The vacuum pad 41 is connected to the vacuum pump 45A by a pipe 49. A valve 46A is arranged between the vacuum pump 45 and the vacuum pad 41. Moreover, the pipe 49 is branched on the way, and the valve 48 for taking in external air is arrange | positioned at the branched pipe.

  The cylinder 42 is provided with a space 42 s for accommodating the vacuum pad 41 at the tip portion thereof. The space 42s is connected to the inert gas supply device 44 and the vacuum pump 45B by a pipe 50 having a branch. A valve 47 is disposed between the space 42s and the inert gas supply device 44, and a valve 46B is disposed between the space 42s and the vacuum pump 45B.

  When the valve 46A is opened with the valve 48 closed and the vacuum pump 45A is activated, the inside of the vacuum pad 41 is decompressed via the pipe 49. As a result, the sealing plug 11 is sucked and held by the vacuum pad 41. On the other hand, when the valve 48 is opened with the valve 46 </ b> A being closed, positive pressure is applied to the vacuum pad 41, and the sealing plug 11 is detached from the vacuum pad 41.

  When the valve 47 is opened with the valve 46B closed, the space 42s is filled with an inert gas. On the other hand, if the valve 46B is opened while the valve 47 is closed and the vacuum pump 45B is operated, the space 42s is depressurized. At this time, if the O-ring 43 disposed at the tip of the cylinder 42 is in close contact with the sealing plate 13, not only the space 42s but also the inside of the case 10 is filled with an inert gas or depressurized. The

The inert gas is injected into the case 10 as follows, for example.
(Step a) First, the case 10 is installed in the inert gas injection device 40. At this time, the cylinder 42 and the vacuum pad 41 are located above the case 10. Further, the valve 46A is opened to operate the vacuum pump 45A, and the sealing plug 11 is sucked and fixed to the vacuum pad 41 (see FIG. 11A).

  (Step b) The cylinder 42 is lowered to bring the O-ring 43 and the sealing plate 13 into close contact. Next, the valve 46B is opened to operate the vacuum pump 45B, and the space 42s and the inside of the case 10 are depressurized. Subsequently, the valve 46B is closed, the valve 47 is opened, and an inert gas is supplied from the inert gas cylinder 44. Thereby, an inert gas is inject | poured into the inside of case 10 of a pressure reduction state from the injection hole 20 (refer FIG. 11B). At this time, the inert gas injection pressure (gauge pressure) is preferably 10 kPa to 100 kPa. The internal pressure of the case 10 into which the inert gas is injected at such a pressure is greater than atmospheric pressure (for example, when the atmospheric pressure is 0 kPa (gauge pressure), it is greater than 0 kPa, preferably 100 kPa or less).

(Step c) When the internal pressure of the case 10 reaches a desired pressure, the vacuum pad 41 is immediately lowered and the sealing plug 11 is inserted into the liquid injection hole 20 (see FIG. 11C). The insertion load per unit area at this time needs to be at least larger than the internal pressure of the case 10. For example, when the opening area of the liquid injection hole 20 is 19.6 mm ² (φ5 mm), the insertion load is approximately 11 N.

  (Step d) After confirming that the sealing plug 11 has been inserted into the injection hole 20, the operation of the vacuum pump 45 is stopped, the valve 46A is closed, and the valve 48 is opened. Thereby, a positive pressure is applied to the inside of the vacuum pad 41 (vacuum breakage), and the sealing plug 11 is detached from the vacuum pad 41. Subsequently, the cylinder 42 is raised (see FIG. 11D).

  When the sealing plug 11 is detached from the vacuum pad 41, the sealing plug 11 is released from the insertion load. Therefore, a gap G <b> 1 is generated between the sealing plate 13 and the holding member 31 due to the repulsive force of the elastic member constituting the protruding portion 32 (see FIG. 6A). However, the airtightness is ensured by the inner peripheral surface 20c of the liquid injection hole 20 and a part of the first side surface portion 34a contacting each other over the entire periphery of the inner peripheral surface 20c. Therefore, the inert gas injected into the case 10 is difficult to escape, and a decrease in the internal pressure of the case 10 is suppressed. Furthermore, since the protrusion P engages with the main surface of the sealing plate 13 on the second opening 20b side, this prevents the sealing plug 11 from coming out of the liquid injection hole 20 any more. Therefore, even if the internal pressure of the case 10 is high, the contact between the first opening 20a and the first side surface 34a is maintained. At this time, the protrusion P is pressed against the sealing plate 13 by the internal pressure of the case 10. When the protrusion P is formed over the entire circumference on the tip side of the protrusion 34, the protrusion P also contributes directly to the improvement of the sealing performance.

  Then, the electrical storage device 100 is moved to a welding apparatus, and the holding member 31 and the sealing plate 13 are joined by welding. Here, as described above, the gap G <b> 1 is formed between the sealing plate 13 and the holding member 31. Therefore, a process of applying a load to the holding member 31 and pushing the sealing plug 11 into the liquid injection hole 20 again to bring the sealing plate 13 and the holding member 31 into close contact (eliminating G1) is performed (step e, (See FIG. 6B). On the other hand, when the sealing plug 11 is pushed in, a gap G2 may be formed between the sealing plate 13 and the protrusion P. Even in this case, since the contact between the first opening 20a and the first side surface 34a is maintained, the escape of the inert gas injected into the case 10 is suppressed. Therefore, a decrease in the internal pressure of the case 10 is suppressed. Subsequently, the sealing plate 13 and the holding member 31 are welded in this state.

  Finally, the sealed power storage device 100 is installed in a decompression chamber, and the amount of inert gas leaking from the power storage device 100 is measured. In this embodiment, since the sealing performance by the sealing plug 11 is excellent, the internal pressure of the case 10 in this leakage inspection is approximately the same as the internal pressure immediately after the sealing plug 11 is inserted into the liquid injection hole 20 in the step (c). Can be maintained. That is, since a leak test can be performed in a state having a high internal pressure, an electricity storage device that passes this test becomes more reliable.

[Electrolytes]
The electrolyte is not particularly limited, and may be selected in consideration of desired performance and the like. Examples of the electrolyte include an electrolyte (organic electrolyte) in which a salt of an alkali metal ion and an anion (alkali metal salt) is dissolved in a nonaqueous solvent (or an organic solvent), and an ionic liquid containing an alkali metal ion and an anion. Is used. The concentration of the alkali metal salt in the nonaqueous electrolyte may be, for example, 0.3 to 3 mol / liter.

The kind of the anion (first anion) constituting the alkali metal salt is not particularly limited. For example, an anion of a fluorine-containing acid [anion of fluorine-containing phosphate such as hexafluorophosphate ion (PF ₆ ⁻ ); Anion of fluorine-containing boric acid such as acid ion (BF ₄ ⁻ )], anion of chlorine-containing acid [perchlorate ion (ClO ₄ ⁻ ), etc.], anion of oxygen acid having an oxalate group [lithium bis (oxalato) Oxalatoborate ions such as borate ions (B (C ₂ O ₄ ) ₂ ⁻ ); Oxalatoborate ions such as lithium tris (oxalato) phosphate ions (P (C ₂ O ₄ ) ₃ ⁻ )], fluoroalkane sulfones anion of acid [trifluoromethanesulfonate ion (CF ₃ SO ₃ ^-), etc.], bissulfonylamide Anion and the like. One alkali metal salt may be used alone, or two or more alkali metal salts having different types of first anions may be used in combination.

  In the present specification, the “ionic liquid” is a molten salt (molten salt), and is used to mean a liquid having ionic conductivity. When an ionic liquid is used for the nonaqueous electrolyte, the content of the ionic liquid in the nonaqueous electrolyte is preferably 80% by mass or more, and more preferably 90% by mass or more. Furthermore, the non-aqueous electrolyte can contain a non-aqueous solvent, an additive and the like in addition to the ionic liquid. On the other hand, when an organic electrolyte is used for the nonaqueous electrolyte, the total amount of the organic solvent and the alkali metal salt in the nonaqueous electrolyte is preferably 80% by mass or more of the nonaqueous electrolyte, and 90% by mass or more. Is more preferable. Further, the non-aqueous electrolyte can contain an ionic liquid, an additive and the like in addition to the organic electrolyte.

  The non-aqueous solvent is not particularly limited, and a known non-aqueous solvent used for an electricity storage device can be used. Non-aqueous solvents include, for example, cyclic carbonates such as ethylene carbonate, propylene carbonate, and butylene carbonate; chain carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate; cyclic carbonates such as γ-butyrolactone. Etc. can be preferably used. A non-aqueous solvent may be used individually by 1 type, and may be used in combination of 2 or more type.

  The ionic liquid containing an alkali metal ion may further contain a second cation in addition to the alkali metal ion (first cation). As such a second cation, an inorganic cation other than an alkali metal, for example, a magnesium ion, a calcium ion, an ammonium cation or the like may be used, but an organic cation is preferable. A 2nd cation can be used individually by 1 type or in combination of 2 or more types.

  Examples of the organic cation used as the second cation include cations derived from aliphatic amines, alicyclic amines and aromatic amines (for example, quaternary ammonium cations), as well as cations having nitrogen-containing heterocycles ( That is, examples include nitrogen-containing onium cations such as cations derived from cyclic amines; sulfur-containing onium cations; and phosphorus-containing onium cations.

[Positive electrode]
The positive electrode includes a positive electrode current collector and a positive electrode active material layer attached to the positive electrode current collector. The positive electrode active material layer includes a positive electrode active material as an essential component, and may include a conductive carbon material, a binder, and the like as optional components.

  In the nonaqueous electrolyte secondary battery, the positive electrode active material exchanges electrons with alkali metal ions (Faraday reaction). Therefore, the positive electrode active material is not particularly limited as long as it is a material that electrochemically occludes and releases alkali metal ions. Such materials include metal chalcogen compounds (sulfides, oxides, etc.), alkali metal-containing transition metal oxides (lithium-containing transition metal oxides, sodium-containing transition metal oxides), alkali metal-containing transition metal phosphates. (Such as iron phosphate having an olivine structure). These materials can be used singly or in combination of two or more.

  In an alkali metal ion capacitor, the positive electrode active material does not exchange electrons with alkali metal ions, and physically adsorbs and desorbs alkali metal ions (non-Faraday reaction). Therefore, the positive electrode active material is not particularly limited as long as it is a material that electrochemically adsorbs and desorbs anions or alkali metal ions. Among these, a carbon material is preferable. Examples of the carbon material include activated carbon, mesoporous carbon, microporous carbon, and carbon nanotube. The carbon material may be activated or may not be activated. These carbon materials can be used singly or in combination of two or more. Of the carbon materials, activated carbon, microporous carbon, and the like are preferable.

  Examples of the microporous carbon include microporous carbon obtained by heating a metal carbide such as silicon carbide or titanium carbide in an atmosphere containing chlorine gas. As activated carbon, the well-known thing used for a lithium ion capacitor can be used, for example. Examples of the raw material of activated carbon include wood; coconut shells; pulp waste liquid; coal or coal-based pitch obtained by thermal decomposition thereof; heavy oil or petroleum-based pitch obtained by thermal decomposition thereof; phenol resin and the like.

  Examples of the conductive auxiliary agent contained in the positive electrode include graphite, carbon black, and carbon fiber. Among these, carbon black is preferable because a sufficient conductive path can be easily formed by using a small amount. Examples of carbon black include acetylene black, ketjen black, and thermal black. The amount of the conductive assistant is preferably 2 to 15 parts by mass, more preferably 3 to 8 parts by mass per 100 parts by mass of the positive electrode active material.

  The binder serves to bind the positive electrode active materials to each other and fix the positive electrode active material to the positive electrode current collector. As the binder, fluororesin, polyamide, polyimide, polyamideimide and the like can be used. As the fluororesin, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, or the like can be used. The amount of the binder is preferably 1 to 10 parts by mass and more preferably 3 to 5 parts by mass per 100 parts by mass of the positive electrode active material.

  As the positive electrode current collector, a metal foil, a non-woven fabric made of metal fibers, a porous metal sheet, or the like is used. The metal constituting the positive electrode current collector is preferably aluminum or an aluminum alloy because it is stable at the positive electrode potential, but is not particularly limited. When using an aluminum alloy, it is preferable that metal components (for example, Fe, Si, Ni, Mn, etc.) other than aluminum are 0.5 mass% or less. The thickness of the metal foil serving as the positive electrode current collector is, for example, 10 to 50 μm, and the thickness of the metal fiber nonwoven fabric or the metal porous sheet is, for example, 100 to 600 μm. A current collecting lead piece 2c (see FIG. 2) may be formed on the positive electrode current collector. The lead piece 2c may be formed integrally with the positive electrode current collector, or a separately formed lead piece may be connected to the positive electrode current collector by welding or the like.

  For example, the positive electrode is applied or filled with a positive electrode mixture slurry containing a positive electrode active material on a positive electrode current collector, and then the dispersion medium contained in the positive electrode mixture slurry is removed. It can be obtained by compressing (or rolling) the current collector holding the. Moreover, as a positive electrode, you may use what is obtained by forming the deposit film of a positive electrode active material on the surface of a positive electrode electrical power collector by vapor phase methods, such as vapor deposition and sputtering. In addition to the positive electrode active material, the positive electrode mixture slurry may contain the above-described binder, conductive additive, and the like.

[Negative electrode]
The negative electrode includes a negative electrode current collector and a negative electrode active material layer attached to the negative electrode current collector. The negative electrode active material layer includes a negative electrode active material as an essential component, and may include a conductive carbon material, a binder, and the like as optional components.

  In the nonaqueous electrolyte secondary battery, the negative electrode active material exchanges electrons with alkali metal ions (Faraday reaction). Therefore, the negative electrode active material is not particularly limited as long as it is a material that occludes and releases alkali metal ions. Examples of the negative electrode active material include, in addition to carbon materials, lithium titanium oxide (such as spinel type lithium titanium oxide such as lithium titanate), alloy-based active material, and sodium-containing titanium compound (spinel type sodium such as sodium titanate). Titanium oxide, etc.). Examples of the carbon material include graphitizable carbon (soft carbon), non-graphitizable carbon (hard carbon), graphite (carbon materials having a graphite-type crystal structure such as artificial graphite and natural graphite), and the like. An alloy-based active material is an active material containing an element that forms an alloy with an alkali metal. For example, zinc, a zinc alloy, a silicon oxide, a silicon alloy, a tin oxide, a tin alloy, etc. are mentioned. A negative electrode active material may be used individually by 1 type, and may be used in combination of 2 or more type. Of the negative electrode active materials, carbon materials are preferable, and graphite and / or hard carbon are particularly preferable.

  Examples of graphite include natural graphite (such as flake graphite), artificial graphite, and graphitized mesocarbon microspheres. Graphite is a layered structure in which planar six-membered rings of carbon are two-dimensionally connected, and has a hexagonal crystal structure. Alkali metal ions can easily move between the layers of graphite and are reversibly inserted into and desorbed from the graphite.

  Hard carbon is a carbon material that does not develop a graphite structure even when heated in an inert atmosphere. Fine graphite crystals are arranged in random directions, and nano-order voids are formed between crystal layers. A material having

  In the alkali metal ion capacitor, the negative electrode active material exchanges electrons with alkali metal ions (Faraday reaction). Therefore, examples of the negative electrode active material include those exemplified as the negative electrode active material of the nonaqueous electrolyte secondary battery, and can be appropriately selected according to the type of alkali metal ion.

  As the binder and the conductive material used for the negative electrode, the materials exemplified as the constituent elements of the positive electrode can be used. The amount of the binder is preferably 1 to 10 parts by mass and more preferably 3 to 5 parts by mass per 100 parts by mass of the negative electrode active material. The amount of the conductive material is preferably 5 to 15 parts by mass and more preferably 5 to 10 parts by mass per 100 parts by mass of the negative electrode active material.

  As the negative electrode current collector, a metal foil, a non-woven fabric made of metal fibers, a porous metal sheet, or the like is used. As the metal, a metal that is not alloyed with sodium can be used. Among these, aluminum, an aluminum alloy, copper, a copper alloy, nickel, a nickel alloy, and the like are preferable because they are stable at the negative electrode potential. Of these, aluminum and aluminum alloys are preferable in terms of excellent lightness. As the aluminum alloy, for example, an aluminum alloy similar to that exemplified as the positive electrode current collector may be used. The thickness of the metal foil serving as the negative electrode current collector is, for example, 10 to 50 μm, and the thickness of the metal fiber nonwoven fabric or metal porous sheet is, for example, 100 to 600 μm. A current collecting lead piece 3c (see FIG. 2) may be formed on the negative electrode current collector. The lead piece 3c may be formed integrally with the negative electrode current collector, or a separately formed lead piece may be connected to the negative electrode current collector by welding or the like.

  The negative electrode is, for example, coated or filled with a negative electrode mixture slurry containing a negative electrode active material on a negative electrode current collector, and then the dispersion medium contained in the negative electrode mixture slurry is removed, and further, if necessary, the negative electrode active material It can be obtained by compressing (or rolling) the current collector holding the. The negative electrode mixture slurry may contain the above-described binder, conductive additive and the like in addition to the negative electrode active material.

[Separator]
A separator can be disposed between the positive electrode and the negative electrode. The material of the separator may be selected in consideration of the operating temperature of the electricity storage device. From the viewpoint of suppressing side reactions with the electrolyte, glass fiber, silica-containing polyolefin, fluororesin, alumina, polyphenylene sulfite (PPS) Etc. are preferably used. Among these, a glass fiber nonwoven fabric is preferable because it is inexpensive and has high heat resistance. Silica-containing polyolefin and alumina are preferable in terms of excellent heat resistance. Moreover, a fluororesin and PPS are preferable in terms of heat resistance and corrosion resistance. In particular, PPS has excellent resistance to fluorine contained in the molten salt.

  The thickness of the separator is preferably 10 μm to 500 μm, more preferably 20 to 50 μm. If the thickness is within this range, an internal short circuit can be effectively prevented, and the volume occupancy of the separator in the electrode group can be kept low, so that a high capacity density can be obtained.

[Example]
Next, based on an Example, this invention is demonstrated more concretely. However, the following examples do not limit the present invention.
[Example 1]
(Preparation of outer can)
A bottomed square outer can 12 (38 mm × 112 mm × 150 mm) was obtained from an aluminum plate having a thickness of 1.5 mm.

(Preparation of sealing plate)
A 37 mm × 111 mm sealing plate 13 was cut out from a 1.5 mm thick aluminum plate by pressing. Simultaneously with the cutting, a hole for taking out the external negative electrode terminal 14 and the external positive electrode terminal 15, a hole for installing the safety valve 16 and the pressure regulating valve 17, and a liquid injection hole 20 were formed. Furthermore, a counterbore 21 (L2: 0.6 mm) was formed around the liquid injection hole 20. The arrangement of each hole is as shown in FIG. The inner diameter HD1 of the inner peripheral surface 20c of the liquid injection hole 20 was 5 mm, and the internal shape was as shown in FIG. 3A.

(Preparation of injection stopper)
A circle having a diameter of 12 mm was cut out from an aluminum plate having a thickness of 0.3 mm to form a holding member 31. The press-fitting member 32 having the shape shown in FIG.
The press-fitting member 32 includes a circular base portion 33 (BD: 6.7 mm, L3: 0.4 mm), a first side surface portion 34a (θ1: 30 °, PD1: 6 mm, PD2: 4.9 mm), and a second side surface portion 34b. (PD3: 3.5 mm, PD5: 5.5 mm, θ2: 25 °). In addition, the cross-sectional area of the hollow S having a substantially cylindrical shape was 5.2 mm ² . The shape press-fitting member 32 The elastic member used for the press-fitting member 32 was EPDM, and the durometer type A had a hardness of Hs70.
The press-fitting member 32 is designed to be in contact with the inner peripheral surface 20c at a part of the first side surface portion 34a, and the diameter PD4 of the contact portion in an unloaded state is 5.7 mm.

(Preparation of positive electrode)
85 parts by mass of NaCrO ₂ (positive electrode active material) having an average particle size of 10 μm, 10 parts by mass of acetylene black (conductive agent) and 5 parts by mass of polyvinylidene fluoride (binder) are added to N-methyl-2-pyrrolidone (NMP). The positive electrode paste was prepared by dispersing. The obtained positive electrode paste was applied to both sides of an aluminum foil having a thickness of 20 μm, sufficiently dried, and rolled to prepare a positive electrode having a total thickness of 180 μm having a positive electrode mixture layer having a thickness of 80 μm on both surfaces.
The positive electrode was cut into a rectangle of size 100 × 100 mm, and 96 positive electrodes 2 were prepared.

(Preparation of negative electrode)
95 parts by mass of hard carbon (negative electrode active material) and 5 parts by mass of polyamideimide (binder) were dispersed in NMP to prepare a negative electrode paste. The obtained negative electrode paste was applied to both sides of an aluminum foil having a thickness of 20 μm, sufficiently dried, and rolled to produce a negative electrode having a total thickness of 150 μm having a negative electrode active material layer having a thickness of 65 μm on both sides.
The negative electrode was cut into a rectangle having a size of 105 × 105 mm, and 97 negative electrodes 3 were prepared.

(Preparation of electrolyte)
The molar ratio (sodium salt: ionic liquid) of sodium bis (fluorosulfonyl) amide (Na · FSA) to 1-methyl-1-propylpyrrolidinium bis (fluorosulfonyl) amide (MPPY · FSA) is 10 : A molten salt electrolyte consisting of a mixture of 90 was prepared.

(Preparation of separator)
A silica-containing polyolefin having a thickness of 50 μm, an average pore diameter of 0.1 μm, and a porosity of 70% was cut into a size of 110 × 110 mm to prepare 194 separators 1.

(Assembly of electricity storage device)
First, the positive electrode 2, the negative electrode 3, and the separator 1 were sufficiently dried by heating at 90 ° C. or higher under a reduced pressure of 0.3 Pa. Thereafter, the separator 1 is interposed between the positive electrode 2 and the negative electrode 3, the positive electrode lead pieces 2c and the negative electrode lead piece 3c overlap each other, and the bundle of the positive electrode lead pieces 2c and the bundle of the negative electrode lead pieces 3c are left and right. Lamination was performed so as to be arranged at a target position, and an electrode group was produced. An electrode having an active material layer (mixture layer) only on one side was disposed at one and the other end of the electrode group so that the active material layer faces the other polarity electrode. Subsequently, the separator 1 was also arranged outside the both ends of the electrode group and accommodated in the outer can 12.

  Next, the sealing plate 13 was fitted into the opening of the outer can 12, and the outer can 12 and the sealing plate 13 were joined by laser welding using a fiber laser. Thereafter, a predetermined amount of electrolyte was injected into the case 10 from the injection hole 20 provided in the sealing plate 13.

  Subsequently, the case 10 was installed in the inert gas injection apparatus shown in FIG. 11A, and helium gas was injected into the case 10 in accordance with the above-described procedures (a) to (d) to obtain a sealed state. The internal pressure of the case 10 immediately after sealing was 40 kPa, and the insertion load for inserting the sealing plug 11 into the liquid injection hole 20 was 11N.

  With respect to the case 10 in the sealed state, the holding member 31 and the sealing plate 13 were joined by spot resistance welding to complete the sodium ion secondary battery A having a nominal capacity of 30 Ah having a structure as shown in FIGS.

[Evaluation]
A simulation was performed to evaluate the sealing performance. Specifically, a simulation was performed using a computer in which information related to the material, shape, and the like of the sealing plug 11 and the sealing plate 13 was input, and the compression ratio of the protruding portion 34 was obtained. Based on this result, the surface pressure of the contact portion SH was obtained, and the sealing performance in the sealed state was evaluated. When the surface pressure is high, it can be evaluated that the sealing performance is excellent. The results are shown in Table 1.

  Further, the pressure resistance in the inserted state and the sealed state was measured. The results are shown in Table 1. The pressure resistance was evaluated by measuring the internal pressure when the injection stopper was removed while making holes in the outer cans of the sodium ion secondary batteries A to C and injecting air from the holes, and evaluating this internal pressure as the pressure resistance.

[Example 2]
A sodium ion secondary battery B was produced and evaluated in the same manner as in Example 1 except that the angle θ1 was 23.5 °. The evaluation results are also shown in Table 1.

[Example 3]
A sodium ion secondary battery C was produced and evaluated in the same manner as in Example 1 except that the angle θ1 was set to 35 °. The evaluation results are also shown in Table 1.

[Example 4]
A sodium ion secondary battery D was prepared and evaluated in the same manner as in Example 1 except that the shape of the injection hole 20 was as shown in FIG. 3B. The evaluation results are shown in Table 2.

[Example 5]
A sodium ion secondary battery E was prepared and evaluated in the same manner as in Example 1 except that the shape of the liquid injection hole 20 was as shown in FIG. 3C. The evaluation results are shown in Table 2.

* Each compression rate of the battery E was calculated | required in two places (the chamfer A and the chamfer B) of the chamfer. Chamfer A is near the upper boundary of the chamfer, and Chamfer B is near the lower boundary of the chamfer.

  According to the present invention, it is possible to maintain high hermeticity in the sealed state of the liquid injection hole of the sealed electric storage device, so that it is required to have long-term reliability, for example, large size for home use or industrial use. It is useful as a power source for power storage devices, electric vehicles, hybrid vehicles, and the like.

1: separator, 2: positive electrode, 2c: positive electrode lead piece, 3: negative electrode, 3c: negative electrode lead piece, 4: nut, 5: washer, 6: collar, 10: case, 11: sealing plug, 12: exterior Can, 13: Sealing plate, 14: External negative terminal, 15: External positive terminal, 17: Pressure regulating valve, 20: Injection hole, 20a: First opening, 20b: Second opening, 20c, 20c ′: Inner peripheral surface, 20d: stepped portion, 20e: chamfered portion, 21: deep spot facing portion, 21B: bottom portion, 31, 31A, 31B, 131: holding member, 32, 132: press-fitting member, 33, 33A, 33B, 133 : Base part, 34, 134: Projection part, 34a, 34Aa, 34Ba, 134a: First side part, 34b, 34Ab, 34Bb, 134b: Second side part, 40: Helium gas injection device, 41: Vacuum pad, 42: Cylinder, 43: O- Ring, 44: helium gas supply device, 45A, 45B: vacuum pump, 46A, 46B, 47, 48: valve, 49 and 50: Pipes, 100: power storage device

Claims (8)

A sealing structure for sealing a liquid injection hole for injecting an electrolyte into a sealed electric storage device,
The sealing structure includes a sealing plate having the liquid injection hole, and a sealing stopper for sealing the liquid injection hole,
The sealing plug includes a plate-shaped holding member that is bonded to the sealing plate, and a press-fit member that includes an elastic material and is bonded to the holding member.
The sealing plate has a counterbore portion around the liquid injection hole on the surface to be joined with the holding member,
The liquid injection hole extends from a first opening on a bottom surface of the deep spot facing portion to a second opening on a flat surface of the sealing plate on which the deep spot facing portion is not formed. Across the sealing plate in the thickness direction,
The press-fitting member includes a base that is joined to the holding member, and a protrusion that is provided so as to protrude from the base and is inserted into the liquid injection hole.
The diameter of the base portion BD and the diameter HD1 of the first opening satisfy the relationship of diameter BD> diameter HD1,
In the sealed state, the protruding portion includes a first side surface portion on the base side of the second opening portion, and a second side surface portion on the tip side of the second opening portion,
A part of the first side surface part and the inner peripheral surface of the liquid injection hole are in contact with each other over the entire circumference of the inner peripheral surface,
An angle θ1 formed by the abutting portion and a direction perpendicular to the main surface of the holding member in an unloaded state is 0 ° or more and 45 ° or less,
The diameter PD1 at the boundary of the protruding portion with the base, the diameter PD3 at the tip, and the diameter HD1 satisfy the relationship of diameter PD1> diameter HD1> diameter PD3,
The maximum diameter PD5 in the second side surface portion of the protrusion and the diameter HD1 satisfy the relationship of diameter PD5> diameter HD1,
The diameter PD2 at the boundary between the first side surface portion and the second side surface portion of the projecting portion and the diameter PD5 satisfy the relationship of diameter PD5> diameter PD2.
A sealed structure for a sealed electrical storage device, wherein a gap L1 is provided between the base and the bottom of the deep spot facing.   The sealed structure of the sealed electric storage device according to claim 1, wherein the protrusion includes a hollow from the tip toward the base.   The hermetic seal according to claim 1 or 2, wherein a ratio HD1 / PD4 between the diameter HD1 and the diameter PD4 of the projecting portion in an unloaded state at the contacting portion is 0.85 to 0.95. Sealed structure for a power storage device. The elastic material comprises ethylene-propylene-diene rubber or fluororubber;
The ethylene-propylene-diene rubber comprises at least one selected from the group consisting of ethylidene norbornene, 1,4-hexadiene, and dicyclopentadiene;
The sealed structure of the sealed electrical storage device according to any one of claims 1 to 3, wherein the elastic material has a durometer type A hardness of 30 to 80 in accordance with JIS K 6253.   The sealed structure of the sealed electrical storage device according to any one of claims 1 to 4, wherein the sealing plate includes a chamfered portion in the vicinity of the first opening. A case comprising the sealing structure according to any one of claims 1 to 5,
A sealed electric storage device including a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte, which are housed in the case.   The sealed electric storage device according to claim 6, wherein the case contains an inert gas, and the pressure in the case is greater than atmospheric pressure. A manufacturing method of a sealed electricity storage device comprising the sealing structure according to any one of claims 1 to 6,
Preparing a bottomed outer can, the sealing plate, and the sealing plug;
Storing the electrode group in the outer can;
Welding the opening end of the outer can in which the electrode group is accommodated and the peripheral edge of the sealing plate;
Impregnating the electrode group with an electrolyte; and
A step of injecting an inert gas from the liquid injection hole of the sealing plate welded to the outer can;
A step of press-fitting the press-fitting member into the liquid injection hole in a state where the inside of the outer can is pressurized by the injected inert gas;
Welding the sealing plate and the sealing plug to each other in a state where the press-fitting member is press-fitted into the liquid injection hole;
Measuring the amount of inert gas leaking from the sealed power storage device. A method for manufacturing a sealed power storage device.

Images