JP5924122B2 - Power storage device - Google Patents

Description

  The present invention relates to a power storage device.

  Conventionally, as a secondary battery which is a kind of power storage device, for example, a lithium ion secondary battery or a nickel-hydrogen secondary battery is well known. For example, in a lithium ion secondary battery, an electrode body is formed by laminating or winding sheet-like electrodes (positive electrode and negative electrode) with a separator interposed therebetween, and this electrode body is combined with a box-shaped main body member. It is set as the structure accommodated in the case which consists of a cover member (for example, patent document 1).

  In Patent Document 1, a main body member and a lid member are welded using a processing laser beam. Further, by providing a groove in the vicinity of the joint between the main body member and the lid member on the upper surface (outside) of the lid member, the heat of welding is prevented from escaping to the lid member. For this reason, it is suppressed that the heat of welding is transmitted in the direction along the surface of the lid member, and welding with a laser beam with a small output is made possible.

JP 2004-39445 A

  By the way, when welding a main body member and a cover member like patent document 1, the heat at the time of welding will be transmitted to the electrode body accommodated in the case, and the separator which constitutes the electrode body will be damaged. There is a fear. For this reason, conventionally, it is expected that heat generated when the case is welded is suppressed from being transmitted to the electrode body, thereby preventing the separator from being damaged.

  This invention is made in view of the said prior art, The objective is to provide the electrical storage apparatus which can suppress that a separator breaks with the heat at the time of welding a case.

In order to solve the above problems, the invention described in claim 1 includes an electrode body in which a positive electrode and a negative electrode are stacked with a separator interposed therebetween, and a case for housing the electrode body and an electrolyte. A power storage device, wherein the case includes a bottom wall and a side wall extending from a peripheral edge of the bottom wall, and is a box-shaped body having an opening on one surface and housing the electrode body; A lid member that covers the opening of the main body member, wherein the main body member has a stepped portion formed around the entire circumference of the opening on the inner side of the distal end portion of the side wall, And a step portion having a thickness smaller than that of the main portion along the peripheral edge portion of the lid member, and the step portion of the main body member and the step portion of the lid member are in contact with each other on two surfaces the Rukoto have in been Awa-fit, the lid member is assembled to said body member A groove portion that opens to the electrode body side is constituted by the main portion, a step portion of the lid member, and the main body member inside the lid member, and the main body member and the lid member are It is welded along the step part of a cover member, and the said groove part is formed over the perimeter of the peripheral part of the said cover member.

According to this, the lid member includes a main portion and a step portion whose plate thickness is thinner than the main portion along the peripheral edge portion of the lid member, and inside the lid member, the main portion, the step portion, The main body member forms a groove portion that opens to the electrode body side, and the main body member and the lid member are welded along the stepped portion. For this reason, on the inner side of the lid member, a space by the groove is formed along the welded portion for welding the main body member and the lid member, and in the region along the joint portion of the inner side of the lid member, The electrode body can be separated. Therefore, when welding a case, it can suppress that a heat | fever is transmitted to an electrode body from a cover member, and can suppress that a separator is damaged by the heat at the time of welding a case. Moreover, since the groove part is formed over the perimeter of the peripheral part of a cover member, it can suppress that a heat | fever is transmitted from a cover member to an electrode body.

  According to a second aspect of the present invention, in the power storage device according to the first aspect, the electrode body has a facing surface facing the inner surface of the lid member, and the groove portion is a peripheral portion of the facing surface. The gist is that they face each other.

  According to this, the groove part has opposed the peripheral part of the opposing surface of the electrode body which opposes the inner surface of a cover member. For this reason, the space by a groove part is interposed between an electrode body and a cover member, and it can suppress more reliably that heat is transmitted from a cover member to an electrode body.

  The invention according to claim 3 is the power storage device according to claim 2, wherein the inner surface of the lid member and the facing surface are in direct contact or indirectly through an insulating sheet. And

According to this, since the inner surface of the lid member and the opposing surface of the electrode body are in direct contact or indirectly through the insulating sheet, heat exchange between the electrode body and the lid member is promoted. it can.
The invention according to claim 4 is the power storage device according to claim 2 or 3, characterized in that an end surface of the electrode body in the stacking direction is the facing surface.

  According to this, the end surface of the electrode body in the stacking direction becomes a facing surface that faces the inner surface of the lid member. Therefore, the separator disposed between the positive electrode and the negative electrode is separated from the cover member as compared with the configuration in which the end faces in the direction along the surfaces of the positive electrode and the negative electrode constituting the electrode body are opposed to the inner surface of the cover member. Further, it is possible to further suppress the separator from being damaged by heat when welding the case.

Invention according to claim 5, in the electricity storage device according to any one of claims 2-4, wherein the cover member and the body member are welded over the entire circumference of the peripheral portion of the lid member Tei Rukoto Is the gist.

According to this, by welding the lid member and the body member over the entire circumference of the peripheral portion of the lid member, Ru can be bonded more firmly.

  According to a sixth aspect of the present invention, in the power storage device according to any one of the second to fifth aspects, the width of the groove is the same as the plate thickness of the main portion adjacent to the groove of the lid member. The gist is that it is formed.

  When the main body member and the lid member are welded, the heat applied to the peripheral edge portion of the outer surface of the lid member is diffused from the portion to which the heat is applied toward the inside (electrode body side) of the lid member. Communicated. According to the present invention, the width of the groove is formed to be the same as the plate thickness of the main part adjacent to the groove of the lid member, so that the heat transferred while diffusing as described above is transmitted to the electrode body. It can suppress suitably. Furthermore, the heat exchange between the electrode body and the lid member is hindered by the groove (space) as compared with the case where the width of the groove is formed to exceed the thickness of the main part adjacent to the groove of the lid member. Can be suppressed.

  A seventh aspect of the present invention is the power storage device according to any one of the first to sixth aspects, wherein the power storage device is a secondary battery. Therefore, the secondary battery of this invention has the effect of the invention as described in any one of Claims 1-6.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that a separator breaks with the heat at the time of welding a case.

The perspective view which shows typically the lithium ion secondary battery decomposed | disassembled partially. The perspective view which shows typically the lithium ion secondary battery partially decomposed | disassembled when seen from the back. The perspective view which shows typically the decomposed | disassembled electrode body. FIG. 1 is a sectional view taken along line 1-1 shown in FIG. The perspective view which shows typically the decomposed | disassembled electrode body in another embodiment. Sectional drawing which shows typically the lithium ion secondary battery in another embodiment.

Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS.
As shown in FIG. 1, a lithium ion secondary battery (hereinafter simply referred to as a “secondary battery”) 11 as a power storage device includes a case 13 that has a generally flat, rectangular parallelepiped shape. . In the following description, the longitudinal direction of the case 13 indicated by the arrow Y1 is indicated as the left-right direction, the height direction of the case 13 indicated by the arrow Y2 is indicated as the vertical direction, and the short direction of the case 13 indicated by the arrow Y3 is indicated as the front-back direction. Show.

  The case 13 includes a bottom wall 14a having a rectangular flat plate shape, and four side walls 14b formed to extend forward from each of four edge portions (peripheral portions) surrounding the bottom wall 14a at right angles. And a main body member 14 having a flat square box shape (bottomed cylindrical shape) having an opening 14c on one surface (one end) as a whole. The main body member 14 is made of a metal material (for example, stainless steel or aluminum). Further, a stepped portion 14d having a stepped shape (stepped shape) is formed over the entire periphery of the opening 14c on the inner side of the distal end portion of each side wall 14b.

  In addition, one of the side walls 14b (the side wall 14b disposed on the upper side in the present embodiment) has a substantially cylindrical shape penetrating the side wall 14b in the thickness direction (vertical direction), and one end of the case 13 A positive electrode terminal 15 and a negative electrode terminal 16 projecting outward are formed. The positive electrode terminal 15 and the negative electrode terminal 16 of the present embodiment are made of a metal material and are fixed in a state of being insulated from the case 13 (main body member 14). In the secondary battery 11 of the present embodiment, charging and discharging are performed via the positive terminal 15 and the negative terminal 16 that are external terminals.

  In addition, the case 13 includes a lid member 17 that is assembled to the main body member 14 and covers the opening 14c of the main body member 14 so as to be sealed. The lid member 17 is made of a metal material (for example, stainless steel or aluminum).

  As shown in FIG. 2, a stepped step portion 17 b is formed on the inner side of the lid member 17 over the entire periphery of the peripheral edge portion of the lid member 17. A main portion 17d is formed on the inner side of the lid member 17 so as to be surrounded by the step portion 17b. In the present embodiment, the plate thickness of the main portion 17d is, for example, 0.8 mm to 4 mm (1 to 5 times the plate thickness of the main body member 14), preferably 1 mm to 3 mm (1 of the plate thickness of the main body member 14). .25 times to 3.75 times).

  The main portion 17 d forms the inner surface 17 a of the flat lid member 17. The vertical dimension (length) of the main part 17d is formed smaller than the vertical dimension (length) of the opening 14c, and the horizontal dimension (length) of the main part 17d is the opening part. It is smaller than the dimension (length) in the left-right direction at 14c.

  As shown in FIG. 1, the lid member 17 includes a step portion 17b formed on the lid member 17 and a step portion 14d formed on the side wall 14b. Is assembled to the main body member 14 in a state of being inserted into the main body member 14. The lid member 17 and the main body member 14 are welded by laser welding over the entire circumference of the peripheral edge of the lid member 17 to form a welded portion 17c along the stepped portion 17b. The welded portion 17c is set at a position substantially coincident with the inner peripheral surface of the opening portion 14c in a front view (viewed from a direction perpendicular to the bottom wall 14a).

  In addition, a rectangular parallelepiped accommodation space Sa is formed between the main body member 14 and the lid member 17. In the housing space Sa formed in the case 13, an electrode comprising a positive electrode sheet 21 as a positive electrode, a negative electrode sheet 31 as a negative electrode, and a separator 18 interposed between the positive electrode sheet 21 and the negative electrode sheet 31. A body 19 is accommodated. In the electrode body 19, a plurality of positive electrode sheets 21 and negative electrode sheets 31 are stacked with the separator 18 interposed therebetween. The electrode body 19 has a rectangular parallelepiped shape that is flat in the vertical direction and the horizontal direction as a whole.

  As shown in FIG. 3, the positive electrode sheet 21 includes a positive electrode metal foil 22 having a rectangular sheet shape. The positive electrode metal foil 22 is made of aluminum, for example. On both surfaces (front surface and rear surface) of the positive electrode metal foil 22, an uncoated region 24 a as an uncoated portion set with a constant width from the upper edge portion 23 that is one side of the positive electrode metal foil 22 over the entire width in the left-right direction. The active material mixture containing the positive electrode active material is applied to the entire surface, thereby forming the positive electrode active material layer 24 (application region 24b) containing the positive electrode active material.

  Further, the positive electrode sheet 21 includes a positive electrode lead portion 25 having a quadrangular shape extending upward from the upper edge portion 23 of the positive electrode metal foil 22. The positive electrode lead portion 25 of this embodiment is formed integrally with the positive electrode metal foil 22 in the positive electrode sheet 21. Further, the positive electrode lead portion 25 is formed on the left side of the upper edge portion 23 in the left-right direction. The positive electrode active material layer 24 is not formed on both surfaces of the positive electrode lead portion 25, and the positive electrode lead portion 25 constitutes a part of the non-application region 24a.

  The negative electrode sheet 31 includes a negative electrode metal foil 32 having a rectangular sheet shape. The negative electrode metal foil 32 is made of copper, for example. On both surfaces (front surface and rear surface) of the negative electrode metal foil 32, an uncoated region 34 a as an uncoated portion set at a constant width from the upper edge portion 33 that is one side of the negative electrode metal foil 32 over the entire width in the left-right direction. The active material mixture containing the negative electrode active material is applied to the entire surface, thereby forming the negative electrode active material layer 34 (application region 34b) containing the negative electrode active material.

  Further, the negative electrode sheet 31 includes a negative electrode lead portion 35 having a quadrangular shape extending upward from the upper edge portion 33 of the negative electrode metal foil 32. The negative electrode lead portion 35 of the present embodiment is formed integrally with the negative electrode metal foil 32 in the negative electrode sheet 31. The negative electrode lead portion 35 is formed on the right side of the upper edge portion 33 in the left-right direction. The negative electrode active material layer 34 is not formed on both surfaces of the negative electrode lead portion 35, and the negative electrode lead portion 35 constitutes a part of the non-application region 34a.

  The separator 18 is made of polypropylene, and is made of polyethylene on both sides of the porous sheet-like base material layer. The separator 18 is a porous sheet-like fine material having a pore structure (pores) finer than that of the base material layer. A three-layer structure in which a pore layer is formed. When the separator 18 reaches the melting point (for example, 135 ° C. to 140 ° C.) of the resin material (polyethylene) constituting the pore layer, the pore layer melts, the pore structure collapses and the pores are blocked. . Thereby, the current (ion passage) between the positive electrode sheet 21 and the negative electrode sheet 31 is interrupted (so-called shutdown function). In the following description, the melting point of polyethylene constituting the pore layer of the separator 18 is particularly referred to as a shutdown temperature.

  The electrode body 19 is formed by alternately laminating the positive electrode sheets 21 and the negative electrode sheets 31 in the front-rear direction (thickness direction) with the separator 18 sandwiched between the positive electrode sheet 21 and the negative electrode sheet 31. . The electrode body 19 of the present embodiment is formed by laminating a plurality (for example, 80 sheets) of positive electrode sheets 21 and a plurality (for example, 81 sheets) of negative electrode sheets 31.

  Moreover, in the electrode body 19, the negative electrode sheet 31 is arrange | positioned at the both ends of the lamination direction. In addition, in the front view, the positive electrode metal foil 22 of each positive electrode sheet 21 is formed smaller than the negative electrode metal foil 32 of each negative electrode sheet 31, and each positive electrode sheet 21 when viewed from the stacking direction in the electrode body 19. The application region 24 b is included in the application region 34 b of the negative electrode sheet 31.

  In the present embodiment, the left-right direction indicated by the arrow Y1 and the vertical direction indicated by Y2 are directions along the surfaces of the positive electrode sheet 21, the negative electrode sheet 31, and the separator 18 (perpendicular to the stacking direction), and the front-rear direction indicated by the arrow Y3 Is the stacking direction of the positive electrode sheet 21, the negative electrode sheet 31, and the separator 18 in the electrode body 19.

  As shown in FIG. 1, in the upper edge portion of the electrode body 19, on the left side of the center in the left-right direction, the positive electrode current collector laminated in the laminating direction without the positive electrode lead portion 25 interposing the separator 18. A portion (positive electrode lead group) 28 is formed. Further, on the right side of the upper edge portion of the electrode body 19 from the center in the left-right direction, there is a negative electrode current collector (negative electrode lead group) 38 that is laminated in the laminating direction without the negative electrode lead portion 35 interposing the separator 18 therebetween. Is formed.

  Moreover, as shown in FIG. 4, the electrode body 19 is accommodated in the accommodation space Sa (main body member 14) in a state of being covered by an insulating bag 13a made of an insulating sheet (insulating film). The insulating sheet forming the insulating bag 13a is formed from a material having a melting point higher than the melting point of the material forming the separator 18 or a thermal decomposition temperature.

  The electrode body 19 is accommodated in the case 13 (main body member 14) in a state where the stacking direction of the positive electrode sheet 21 and the negative electrode sheet 31 forming the electrode body 19 and the extending direction of the side wall 14b are matched. . That is, the electrode body 19 is accommodated in the main body member 14 in a state in which the insertion direction of the electrode body 19 with respect to the main body member 14 (the direction from the opening 14c toward the bottom wall 14a) and the stacking direction of the electrode body 19 are aligned. Yes.

  The electrode body 19 is accommodated in the case 13 with the end faces (the front face 19a in this embodiment) of the positive electrode sheet 21 and the negative electrode sheet 31 forming the electrode body 19 along the inner face 17a of the lid member 17. ing. That is, in the case 13, the electrode body 19 is in a state where the front surface 19 a faces the inner surface 17 a of the lid member 17 and the rear surface 19 b faces the inner surface 14 e of the bottom wall 14 a with the insulating bag 13 a sandwiched therebetween. Is arranged. In the present embodiment, the front surface 19a of the electrode body 19 is a facing surface.

  The front surface 19a of the electrode body 19, the insulating bag 13a, and the inner surface 17a of the lid member 17 are in surface contact with each other. The rear surface 19b of the electrode body 19, the insulating bag 13a, and the inner surface 14e of the bottom wall 14a are in surface contact with each other. That is, the front surface 19a of the electrode body 19 and the inner surface 17a of the lid member 17, and the rear surface 19b of the electrode body 19 and the inner surface 14e of the bottom wall 14a are in indirect contact via the insulating bag 13a.

  As shown in FIG. 1, the positive electrode current collector 28 (positive electrode lead portion 25) is, for example, resistance welded to one end (tip) of a positive electrode current collector terminal 40 as a current collecting member having a rectangular flat plate shape. Are joined and electrically connected. The other end (base end) of the positive electrode current collecting terminal 40 is connected to and electrically connected to the other end (base end) side of the positive electrode terminal 15 protruding into the housing space Sa of the case 13.

  The negative electrode current collector 38 (negative electrode lead part 35) is joined and electrically connected to one end (tip) of the negative electrode current collector terminal 41 as a current collecting member having a rectangular flat plate shape by, for example, resistance welding. ing. Further, the other end (base end) of the negative electrode current collecting terminal 41 is connected to and electrically connected to the other end (base end) side of the negative electrode terminal 16 protruding into the housing space Sa of the case 13. The case 13 (accommodating space Sa) is filled with an electrolyte (electrolytic solution).

  As shown in FIG. 4, on the inner side of the lid member 17, a groove 45 that is surrounded by the stepped portion 17 b, the main portion 17 d, and the main body member 14 and opens to the electrode body 19 side is formed between the lid member 17 and the main body member 14. It is formed along the welding part 17c. The groove portion 45 of the present embodiment is configured by forming a step portion 17b having a plate thickness thinner than that of the main portion 17d in a range wider than a fitting portion with each side wall 14b. The groove 45 constitutes a space Sb between the accommodation space Sa for accommodating the electrode body 19 and the stepped portion 17b. In addition, the plate | board thickness of the step part 17b is 1/2 of the main part 17d adjacent to the step part 17b, for example.

  Further, the groove 45 has a certain width (a direction along the surface of the lid member 17 and orthogonal to the peripheral edge of the lid member 17) from the inner circumferential surface of the opening 14c (the circumferential edge of the lid member 17). Is formed. The width of the groove portion 45 is formed to have the same dimension as the plate thickness of the main portion 17 d that is a non-formation region of the groove portion 45 in the lid member 17. The width of the groove 45 is, for example, 0.8 mm to 4 mm, and preferably 1 mm to 3 mm.

  Here, in the present embodiment, the main body member 14 and the lid member 17 irradiate the processing laser beam 46 along the welded portion 17c from the direction orthogonal to the outer surface of the lid member 17, thereby the lid member. The welded portion 17c in 17 and the stepped portion 14d in the side wall 14b are melted and welded. The heat generated by irradiating the laser beam 46 to the welded portion 17c is mainly directed from the irradiation point (part) of the laser beam 46 toward the electrode body 19 side, with the irradiation point of the laser beam 46 as the apex. When viewed from a direction orthogonal to the irradiation direction 46, the lid member 17 is transmitted so as to form a conical shape having an apex angle of 90 ° (indicated by a broken line in the figure).

  As described above, the groove portion 45 of the present embodiment has a width that is the same as the plate thickness of the main portion 17 d of the lid member 17. For this reason, the opening (opening region) of the groove 45 is formed on the inner side of the lid member 17 from the intersection of the axis passing through the welded portion 17c and orthogonal to the outer surface of the lid member 17 and the outer surface of the lid member 17 to the axis. On the other hand, it can be said that it is formed in the projection part (projection region) in the range of 45 °.

  Then, when viewed from the front, both left and right edges of the front surface 19a of the electrode body 19 are respectively positioned at substantially the center of the groove 45 formed at both edges in the left and right direction of the lid member 17. Similarly, the lower edge portion of the front surface 19 a of the electrode body 19 is located at the approximate center of the groove portion 45 formed in the lower edge portion of the lid member 17. That is, in the present embodiment, the groove 45 is formed so as to face the peripheral edge of the front surface 19 a of the electrode body 19.

Next, the operation of the secondary battery 11 configured as described above will be described.
As shown in FIG. 4, the secondary battery 11 of the present embodiment is set on the outer surface of the lid member 17 in a state where the electrode body 19 is accommodated in the accommodation space Sa and the lid member 17 is assembled to the main body member 14. It is formed by irradiating the processing laser beam 46 along the welded portion 17 c and welding the main body member 14 and the lid member 17.

  At this time, the heat generated in the welded portion 17c by the irradiation of the laser beam 46 is transmitted from the irradiation point of the laser beam 46 to the electrode body 19 side (indicated by a broken line in the drawing). However, a groove 45 is formed inside the lid member 17 along the welded portion 17c. For this reason, the space Sb by the groove part 45 is formed inside the lid member 17 along the welded part 17 c, and thus the lid member in the area (groove part 45) along the welded part 17 c of the inside of the lid member 17. 17 and the electrode body 19 can be separated. For this reason, when the case 13 is welded, it is possible to prevent heat from being transmitted from the lid member 17 to the electrode body 19.

  As described above, when the temperature of the separator 18 constituting the electrode body 19 reaches the shutdown temperature, the pore layer melts and the shutdown function works. If heat at the time of welding the case 13 is transmitted to the electrode body 19 and the temperature of the electrode body 19 reaches the shutdown temperature, a shutdown occurs in the separator 18 and the internal resistance of the secondary battery 11 is increased. The problem that becomes high occurs.

  However, in the present embodiment, heat at the time of welding the case 13 is suppressed from being transmitted to the electrode body 19, and the separator 18 is melted at the time of welding the case 13, or a shutdown function is provided with the melting of the separator 18. It can suppress suitably that the separator 18 breaks, such as working.

  Further, the lid member 17 and the main body member 14 are welded at a welded portion 17 c set along the peripheral edge of the lid member 17, and the groove portion 45 is opposed to the inner surface 17 a of the lid member 17. Is formed to face the peripheral edge of the front surface 19a. For this reason, space Sb (groove part 45) is interposed between the electrode body 19 and the cover member 17, and it can suppress more reliably that heat is transmitted from the cover member 17 to the electrode body 19.

  Further, since the inner surface 17a of the lid member 17 and the front surface 19a of the electrode body 19 are in indirect contact via the insulating bag 13a, the electrode body 19 and the lid member 17 are interposed via the front surface 19a. The heat exchange performed can be promoted. That is, in the present embodiment, the electrode body 19 and the lid member 17 can be thermally coupled to each other (in a heat exchangeable manner). In the present embodiment, the electrode body 19 and the bottom wall 14a are also indirectly contacted via the insulating bag 13a and are thermally coupled to each other (in a heat exchangeable manner).

  In the present embodiment, the end surface (front surface 19 a) in the stacking direction of the positive electrode sheet 21 and the negative electrode sheet 31 constituting the electrode body 19 faces the inner surface 17 a of the lid member 17. For this reason, compared with the structure which makes the end surface of the direction along the surface of the electrode body 19 (perpendicular to a lamination direction) oppose the inner surface 17a of the cover member 17, it is arrange | positioned between the positive electrode sheet 21 and the negative electrode sheet 31. The separator 18 can be separated from the welded portion 17c (lid member 17).

  Moreover, in this embodiment, since the cover member 17 and the main body member 14 are welded over the perimeter of the peripheral part in the cover member 17, it can join the cover member 17 and the main body member 14 more firmly. it can. And even if it is a case where such a structure is employ | adopted, since the groove part 45 is formed over the whole welding part 17c formed along the peripheral part of the cover member 17, heat | fever is from the cover member 17. Transmission to the electrode body 19 can be suppressed.

  The width of the groove 45 is formed to have the same dimension as the plate thickness of the main portion 17 d of the lid member 17. As described above, the heat generated by the irradiation of the laser beam 46 is transmitted while being diffused at an angle of 90 ° from the irradiation point (welded portion 17c) of the laser beam 46. In contrast, in the present embodiment, the groove 45 (space Sb) is interposed over substantially the entire heat transfer range of the lid member 17 by forming the width of the groove 45 to be the same as the plate thickness of the main portion 17d. ing. Therefore, when the case 13 is welded, heat can be suitably suppressed from being transmitted from the lid member 17 to the electrode body 19.

  Here, for example, when the width of the groove 45 is formed to a dimension exceeding the plate thickness of the main portion 17 d, the heat is further prevented from being transferred from the lid member 17 to the electrode body 19 when the case 13 is welded. It is considered possible. However, when such a configuration is adopted, when the secondary battery 11 is used, heat transfer between the lid member 17 and the electrode body 19 is prevented even when the temperature of the secondary battery 11 is adjusted, There is a possibility that the temperature of the secondary battery 11 cannot be appropriately adjusted.

  On the other hand, the groove 45 (space Sb) of the present embodiment is formed on the inner side of the lid member 17 only in a region along the peripheral edge of the lid member 17 (inner circumferential surface of the opening 14c). It is formed with the same width as the plate thickness. That is, in the present embodiment, the groove 45 (space Sb) is formed only at the peripheral edge of the lid member 17 where heat due to the irradiation of the laser light 46 is easily transmitted. For this reason, in this embodiment, while suppressing the transfer of heat at the time of welding of the case 13, the heat transfer at the time of temperature adjustment can be suitably performed during use as the secondary battery 11. ing. Furthermore, in the lid member 17 of the present embodiment, the plate thickness is ensured in the entire main portion 17d excluding the groove portion 45, so that the strength of the lid member 17 can be suitably maintained.

  And in the secondary battery 11 of this embodiment, as a result of being able to suppress that the separator 18 is damaged by the heat | fever at the time of welding the case 13 as the secondary battery 11, as a result of the fall of the electrical capacity resulting from the failure | damage of the said separator 18 Along with this, it is possible to suppress the charging cycle from being shortened. Further, since the temperature can be easily adjusted as the secondary battery 11, it is preferable that the electric capacity of the secondary battery 11 is reduced by adjusting the temperature to a temperature suitable for the operation of the secondary battery 11. Can be suppressed.

Therefore, according to the present embodiment, the following effects can be obtained.
(1) The case 13 is formed by welding the lid member 17 and the main body member 14, and a groove portion 45 opening on the electrode body 19 side is formed inside the lid member 17. And is formed along the welded portion 17c. For this reason, a space Sb is formed by the groove 45 along the welded portion 17c on the inner side of the lid member 17, whereby the lid member 17 and the electrode body are formed in the region along the welded portion 17c on the inner side of the lid member 17. 19 can be separated. Accordingly, when welding the case 13, it is possible to suppress heat from being transmitted from the lid member 17 to the electrode body 19, and to prevent the separator 18 from being damaged by heat when welding the case 13.

  (2) The lid member 17 and the main body member 14 are welded along the peripheral edge portion (welded portion 17c) of the lid member 17, and the groove portion 45 is formed on the electrode body 19 facing the inner surface 17a of the lid member 17. It is formed to face the peripheral edge portion of the front surface 19a. For this reason, the space Sb by the groove 45 is interposed between the electrode body 19 and the lid member 17, and heat can be more reliably suppressed from being transmitted from the lid member 17 to the electrode body 19.

  (3) Since the inner surface 17a of the lid member 17 and the front surface 19a of the electrode body 19 are indirectly in contact via the insulating bag 13a, heat exchange between the electrode body 19 and the lid member 17 is performed. Can promote. Therefore, the temperature of the secondary battery 11 can be adjusted more easily.

  (4) The end surface (front surface 19 a) in the stacking direction of the electrode body 19 faces the inner surface 17 a of the lid member 17. For this reason, compared with the configuration in which the end surface in the direction orthogonal to the stacking direction of the electrode body 19 (the direction along the surfaces of the positive electrode sheet 21 and the negative electrode sheet 31) is opposed to the inner surface 17a of the lid member 17, The separator 18 disposed between the negative electrode sheets 31 is separated from the welded portion 17c (the lid member 17), and it is possible to further suppress the separator 18 from being broken (melted) by heat when welding the case 13.

  (5) By welding the lid member 17 and the main body member 14 over the entire circumference of the peripheral edge portion (welded portion 17c) of the lid member 17, the lid member 17 and the main body member 14 can be joined more firmly. Even when such a configuration is adopted, the groove 45 is formed over the entire circumference of the welded portion 17 c formed along the peripheral edge of the lid member 17. Can be prevented from being transmitted to the electrode body 19.

  (6) The width in the direction perpendicular to the peripheral edge of the lid member 17 in the groove 45 is formed to have the same dimension as the plate thickness of the main portion 17d in the lid member 17. For this reason, it can suppress suitably that the heat transmitted while diffusing to the electrode body 19 side from the irradiation point (welding part 17c) of the laser beam 46 is transmitted to the electrode body 19. Furthermore, compared with the case where the width of the groove portion 45 is formed to be larger than the plate thickness of the main portion 17d of the lid member 17, heat exchange between the electrode body 19 and the lid member 17 is caused by the groove portion 45 (space Sb). It is possible to suppress the obstruction.

(7) As the secondary battery 11, it is possible to prevent the separator 18 from being damaged by heat when welding the case 13, and to easily adjust the temperature of the electrode body 19.
(8) As a result of suppressing the separator 18 from being damaged by heat when the case 13 is welded as the secondary battery 11, the charge cycle is shortened as the electric capacity is reduced due to the damage of the separator 18. Can be suppressed. In addition, since the temperature can be easily adjusted as the secondary battery 11, it is suitably suppressed that the electric capacity of the secondary battery 11 is reduced by adjusting the temperature to a temperature suitable for the operation of the secondary battery 11. can do.

The embodiment is not limited to the above, and may be embodied as follows, for example.
As shown in FIG. 5, the electrode body 19 has a positive electrode sheet 21, a negative electrode sheet 31, and a separator 18 formed in a strip shape (long sheet shape), and these are wound in a spiral shape to form the positive electrode sheet 21. Further, the negative electrode sheet 31 may be formed to have a laminated structure. In this case, on the upper edge portion 23 of the positive electrode sheet 21, the positive electrode lead portions 25 are extended and formed at predetermined intervals in the length direction of the positive electrode sheet 21, while the negative electrode sheet 31 is formed on the upper edge portion 33 of the negative electrode sheet 31. The negative electrode lead portions 35 are extended and formed at predetermined intervals in the length direction of 31.

  And by winding in the state which laminated | stacked the separator 18, the positive electrode sheet 21, and the negative electrode sheet 31, the some positive electrode lead part 25 does not pinch | interpose the separator 18 in the left side of the upper edge part in the electrode body 19. A positive electrode current collector 28 having a layered structure in the state is formed extending upward. Further, on the right side of the upper edge portion of the electrode body 19, a negative electrode current collector portion 38 having a layered structure (layered shape) in a state where the plurality of negative electrode lead portions 35 do not sandwich the separator 18 therebetween is formed.

  As shown in FIG. 6, the positive terminal 15 and the negative terminal 16 may be formed on the lid member 17. In this case, the main body member 14 is formed in a bottomed cylindrical shape having an opening 14c on the upper surface. The electrode body 19 extends in the direction along the surfaces of the positive electrode sheet 21 and the negative electrode sheet 31 and extends in the positive electrode current collector 28 (positive electrode lead part 25) and the negative electrode current collector 38 (negative electrode lead part 35). (The vertical direction here) is accommodated in the case 13 in a state in which the extending direction of the side wall 14b (here, the vertical direction) is matched. And it is good to form the groove part 45 inside the cover member 17 along the welding part 17c. Even if it forms in this way, it can suppress that the heat at the time of welding case 13 is transmitted to the electrode body 19 from the cover member 17. FIG. In the present alternative example, an end surface (here, an upper end surface) of the electrode body 19 in a direction along the surfaces of the positive electrode sheet 21 and the negative electrode sheet 31 constituting the electrode body 19 is opposed to the inner surface 17a. Become.

  In place of the insulating bag 13a, a sheet-like insulating sheet (insulating film) may be interposed between the electrode body 19 and the lid member 17 and between the electrode body 19 and the bottom wall 14a. Further, the insulating bag 13a may be omitted. In this case, the front surface 19a of the electrode body 19 and the inner surface 17a of the lid member 17 may be brought into direct contact and thermally connected.

  The groove 45 may be formed intermittently as long as it is formed along the welded portion 17 c inside the lid member 17. Further, the groove 45 may be omitted in a region that does not face the front surface 19 a of the electrode body 19.

The groove 45 may be formed away from the inner peripheral surface of the opening 14 c in the main body member 14.
The width of the groove 45 may be formed to be smaller or larger than the plate thickness of the main portion 17d. That is, the groove part 45 should just be formed along the welding part 17c.

  The welding part 17c should just be set along the peripheral part of the cover member 17, and is not corresponded with the internal peripheral surface of the opening part 14c in front view (viewing from a direction perpendicular | vertical to the bottom wall 14a). May be.

The case 13 (the main body member 14 and the lid member 17) may be welded using, for example, arc welding.
O Although it was set as the positive electrode metal foil 22, it may be a thin plate having a thickness that does not affect the reduction of the electric capacity (battery capacity) in the secondary battery 11 or the production of the battery. The negative electrode metal foil 32 can be similarly changed.

The number of the positive electrode sheet 21 and the negative electrode sheet 31 constituting the electrode body 19 may be changed as appropriate.
The shape of the case 13 (main body member 14) may be formed in a columnar shape or an elliptical column shape that is flat in the left-right direction.

  The present invention may be embodied as a nickel hydride secondary battery as a power storage device and a secondary battery, or an electric double layer capacitor as a power storage device.

  DESCRIPTION OF SYMBOLS 11 ... Lithium ion secondary battery (secondary battery, electrical storage apparatus), 13 ... Case, 13a ... Insulating bag (insulating sheet), 14 ... Main body member, 14a ... Bottom wall, 14b ... Side wall, 14c ... Opening part, 17 ... Lid member, 17a ... inner surface, 17b ... stepped portion, 17c ... welded portion, 17d ... main part, 18 ... separator, 19 ... electrode body, 19a ... front surface (opposite surface), 21 ... positive electrode sheet (positive electrode), 31 ... negative electrode Sheet (negative electrode), 45 ... groove portion.

Claims (7)

A power storage device comprising: an electrode body in which a positive electrode and a negative electrode are stacked with a separator interposed therebetween; and a case for housing the electrode body and an electrolyte,
The case includes a bottom wall and a side wall extending from the peripheral edge of the bottom wall, and has a box-like shape having an opening on one surface, and a body member that houses the electrode body, and an opening of the body member A lid member covering
The main body member has a stepped portion formed on the inner side of the front end portion of the side wall over the entire circumference of the opening.
The lid member includes a main part and a step part having a plate thickness thinner than the main part along a peripheral part of the cover member, and the step part of the main body member and the step part of the cover member are mutually connected. the Rukoto is Awa-fitted while being in contact with two faces, the cover member is assembled to said body member,
Inside the lid member, a groove that opens to the electrode body side is constituted by the main portion, a stepped portion of the lid member, and the main body member, and the main body member and the lid member are stepped on the lid member. Welded along the section,
The power storage device, wherein the groove is formed over the entire periphery of the peripheral edge of the lid member. The electrode body has a facing surface facing the inner surface of the lid member,
The power storage device according to claim 1, wherein the groove portion is opposed to a peripheral edge portion of the facing surface.   The power storage device according to claim 2, wherein the inner surface of the lid member and the facing surface are in direct contact or indirectly through an insulating sheet.   The power storage device according to claim 2 or 3, wherein an end surface of the electrode body in the stacking direction is the facing surface. Power storage device according to any one of the lid member and the body member and the lid claim Ru Tei is welded over the entire circumference of the peripheral portion of the member 2 to 4 and. 6. The power storage device according to claim 2, wherein a width of the groove portion is formed to have the same dimension as a plate thickness of a main portion adjacent to the groove portion of the lid member.   The power storage device according to claim 1, wherein the power storage device is a secondary battery.