HK1144032B - Electric energy storage device and its manufacturing method - Google Patents

Description

Electricity storage device and method for manufacturing same

Technical Field

The present invention relates to an electric storage device such as a lithium ion battery, a lithium secondary battery, a polymer secondary battery, and an electric double layer capacitor.

Background

Conventionally, in connection with an electric storage device such as a lithium ion battery, demands for downsizing, weight reduction, shape freedom, and the like have been increasing with the expansion of various applications.

Therefore, in view of such a demand, the following lightweight, thin and flexible sheet-like lithium ion secondary batteries have been proposed: as the battery case, a flexible exterior body is formed by a multilayer laminated film having a back surface layer made of a thermoplastic resin having excellent electrolyte resistance and heat sealability, such as polyethylene or polypropylene, on the inner surface side, and a sheet-like inner electrode pair and an electrolyte are sealed in the exterior body; an intermediate layer made of a metal foil having excellent flexibility and strength, such as an aluminum foil, is provided in the middle; further, the outer surface side has an outer surface layer made of an insulating resin having excellent electrical insulation properties, such as a polyamide resin (see, for example, patent documents 1 and 2).

Here, patent document 1 discloses a sheet-shaped battery having: the external packaging body is held between the inner lead and the outer lead in a strong and airtight state, and the sealing performance and the connection reliability are improved.

Patent document 2 discloses a battery having: the battery pack includes an electrode body having a protruding portion that penetrates the outer package body and protrudes outside the battery, a seal portion provided around the protruding portion, and an insulating member provided at a portion of the protruding portion that contacts the outer package body. More specifically, after the protrusion 41 is protruded from the outer film 3, the sealing portion 5 for sealing the gap between the protrusion 41 and the outer film 3 over the entire periphery of the protrusion 41 is provided, thereby preventing a short circuit due to contact between the protrusion 41 and the metal foil of the outer film 3 when the protrusion 41 of the external terminal 4 penetrates the outer film 3.

Patent document 1: japanese unexamined patent publication No. 2003-151529

Patent document 2: japanese unexamined patent publication No. 2003-331819

However, the batteries disclosed in patent document 1 or patent document 2 may have the following problems.

For example, in the battery disclosed in patent document 1, since the through hole of the outer package 2 and the rivet shaft diameter of the rivet 7a are made substantially equal, insulation breakage occurs between the outer package 2 and the rivet shaft of the rivet 7a with recent use under high voltage, and as a result, an internal short circuit occurs between the aluminum foil intermediate layer 2b and the rivet shaft of the rivet 7 a.

In the battery disclosed in patent document 2, the metal protruding portion 41 is sealed with a separate nut or resin, which causes a problem in long-term sealing reliability. Further, the separate sealing portion 5 (insulating member) needs to be provided for each of the protruding portions 41, which causes problems in cost increase and workability with an increase in the number of parts and working steps.

Disclosure of Invention

The present invention has been made in view of the above-described problems of the conventional art, and an object of the present invention is to provide an electric storage device having a connection structure with high connection reliability and capable of preventing contact between an outer package and a connection terminal with a simple configuration.

In order to achieve the above object, a first aspect of the present invention provides an electric storage device including: a battery element housed in an exterior body having at least a metal layer; a plate-shaped inner lead connected to the battery element inside the outer package; a plate-shaped external lead arranged outside the outer package body so as to face the internal lead; a connection terminal electrically connecting the inner lead and the outer lead; an inner insulating member provided between the outer package and the inner lead along an inner surface of the outer package; and an outer insulating member provided between the outer package and the outer lead along an outer surface of the outer package so as to face the inner insulating member, wherein the connection terminal has a through shaft through which the outer lead, the outer insulating member, the outer package, the inner insulating member, and the inner lead are respectively passed, and collar portions integrally formed at both end portions of the through shaft, and the collar portions at both end portions of the connection terminal press-sandwich the outer insulating member, the outer package, and the inner insulating member via the plate-shaped outer lead and the inner lead, and press-fit the outer insulating member and/or the inner insulating member between the through shaft of the connection terminal and the metal layer of the outer package.

The integrally formed collar portion is a portion formed in a flange shape at an end portion of the metal through shaft, and the flange-shaped portion is integrally formed of the same member as the through shaft and has a cross-sectional area larger than a cross-sectional area of the through shaft in a diameter direction.

A second aspect of the present invention is the power storage device according to the first aspect, wherein the diameter of each of the through holes of the outer insulating member and the inner insulating member through which the through shaft of the connection terminal penetrates is formed to be substantially equal to the diameter of the through shaft, and the diameter of the through hole of the outer package through which the through shaft of the connection terminal penetrates is formed to be larger than the diameter of the through shaft in advance.

A third aspect of the present invention is the electric storage device according to the first or second aspect, wherein the exterior body is a multilayer exterior body having a heat-sealable inner surface layer made of a thermoplastic resin on an inner surface thereof, and the inner insulating member covers at least a part of any one of the battery element, the internal lead, and the connection terminal, thereby serving also as an inner surface layer protection means for preventing damage to the inner surface layer of the multilayer exterior body.

In a fourth aspect of the present invention, in addition to the third aspect, the inner insulating member covers an end portion of the inner lead that is close to an inner surface layer of the multilayered outer package in a longitudinal direction of the inner lead.

A fifth aspect of the present invention provides an electric storage device according to the third or fourth aspect, wherein the inner insulating member covers a flange portion of the connection terminal close to an inner surface layer of the multilayered outer package.

A sixth aspect of the present invention provides an electric storage device as defined in any one of the third to fifth aspects, wherein the inner insulating member is formed in a substantially コ -shaped cross section by a portion along an inner surface layer of the multilayered outer package, a portion covering an end portion of the inner lead, and a portion covering a flange portion of the connection terminal.

A seventh aspect of the present invention provides the power storage device of any one of the first to sixth aspects, wherein a plurality of the connection terminals are provided for the plate-shaped external lead and the internal lead, respectively.

An eighth aspect of the present invention provides the electricity storage device as defined in any one of the first to seventh aspects, wherein the connection terminals are rivets respectively coupled to the plate-shaped external lead and the internal lead.

A ninth aspect of the present invention provides the electric storage device as defined in any one of the first to eighth aspects, wherein the connection terminal is formed of at least the same material as the inner lead.

A tenth aspect of the present invention provides an electricity storage device according to any one of the first to ninth aspects, wherein the inner insulating member is formed of polypropylene, polyethylene, polystyrene, polyamide, or ionomer having a higher melting point than the heat-sealable inner layer.

An eleventh aspect of the present invention provides an electric storage device according to any one of the first to tenth aspects, wherein the electric storage device is a lithium ion battery used at a high voltage of 100V or more.

A twelfth aspect of the present application provides a method of manufacturing an electric storage device, the electric storage device including: a battery element housed in an exterior body having at least a metal layer; a plate-shaped inner lead connected to the battery element inside the outer package; a plate-shaped external lead arranged outside the outer package body so as to face the internal lead; a connection terminal electrically connecting the inner lead and the outer lead; an inner insulating member provided between the outer package and the inner lead along an inner surface of the outer package; an outer insulating member provided between the outer package and the outer lead along an outer surface of the outer package so as to face the inner insulating member, wherein a connection terminal having a through shaft and a collar formed in advance at one end of the through shaft is used, a diameter of each of through holes of the outer lead, the outer insulating member, the inner insulating member, and the inner lead through which the through shaft of the connection terminal is inserted is formed to be substantially equal to a diameter of the through shaft, a diameter of each of through holes of the outer package through which the through shaft of the connection terminal is inserted is formed to be larger than the diameter of the through shaft, the through shaft of the connection terminal is inserted into each of the through holes of the outer lead, the outer insulating member, the outer package, the inner insulating member, and the inner lead, and the other end of the through shaft is swaged, a new collar portion is formed, and caulking pressure is applied to the outer insulating member, the outer package, and the inner insulating member via the plate-shaped outer lead and the inner lead, so that the outer insulating member and/or the inner insulating member is pressed into a space between the through hole of the outer package and the through shaft, which are formed in a large size in advance.

A thirteenth aspect of the present invention provides, in addition to the twelfth aspect, a method of manufacturing an electric storage device, wherein the outer package is a multilayer outer package having a heat-sealable inner surface layer made of a thermoplastic resin on an inner surface thereof, and after the outer lead, the outer insulating member, the outer package, the inner insulating member, and the inner lead are connected using the connection terminal, the inner insulating member is folded back at an end portion of the inner lead, and the end portion of the inner lead, the end portion of the battery element, and a flange portion of the connection terminal are covered so as to follow a surface of the end portion of the inner lead, the end portion of the battery element, and the flange portion of the connection terminal, and then the outer package is housed in the outer package.

According to the electric storage device of the first aspect of the present application, since the connection terminal having the collar portion formed integrally with the through shaft is pressed and held against the external lead, it is possible to ensure good sealing between the connection terminal and the external lead, and by press-fitting the outer insulating member and/or the inner insulating member between the through shaft and the metal layer of the outer package, it is possible to reliably prevent contact between the through shaft of the connection terminal and the metal layer of the outer package, and it is possible to realize an electric storage device having high insulation reliability with a simple configuration. Further, the step of filling a separate insulating member between the metal layer of the outer package and the through-shaft in advance or filling the insulating member after connection can be omitted, which contributes to improvement in workability and reduction in cost.

According to the electricity storage device of the second aspect of the present application, a gap can be formed between the through shaft of the connection terminal and the metal layer of the exterior body, and the press-fitting of the outer insulating member and/or the inner insulating member by the caulking pressure can be reliably facilitated with a simple configuration.

According to the electricity storage device of the third aspect of the present application, the inner insulating member serves also as an inner layer protection device for preventing damage due to contact between the metal member such as the battery element, the internal lead, and the connection terminal and the inner layer, and therefore, it is possible to effectively suppress a decrease in productivity and an increase in cost accompanying the addition of the number of components and the number of working steps, and to prevent contact between the metal member and the metal layer of the outer package body accompanying damage to the inner layer.

According to the power storage device of the fourth aspect of the present application, since the end portion of the inner lead, which may damage the inner surface layer, is covered in the longitudinal direction thereof, direct contact between the inner surface layer and the end portion of the inner lead can be prevented.

According to the power storage device of the fifth aspect of the present invention, since the inner flange portion of the connection terminal, which may damage the inner surface layer, is covered, direct contact between the inner surface layer and the inner flange portion can be prevented.

According to the power storage device of the sixth aspect of the present application, since the inner insulating member is formed in a substantially コ -shaped cross section, when the portion (upper portion in the コ -shaped form) of the inner insulating member along the inner surface of the outer package is sandwiched between the inner lead and the outer package, the portion (side portion in the コ -shaped form) covering the end portion of the inner lead and the portion (lower portion in the コ -shaped form) covering the inner flange portion can be fixed without using an adhesive or the like, and therefore positioning can be performed easily.

According to the power storage device of the seventh aspect of the present invention, for example, in comparison with a configuration in which only one connection terminal is provided for each of the plate-shaped outer lead and the plate-shaped inner lead, by providing a plurality of connection terminals, it is possible to improve the connection reliability with the outer lead, and in addition, in comparison with a configuration in which a plurality of separate insulating members are provided so as to surround each of the plurality of through shafts, it is possible to further improve the connection workability with the outer lead.

According to the power storage device of the eighth aspect of the present application, the rivet is used as the connection terminal, whereby the inner lead and the outer lead can be respectively joined by a relatively simple and economical method.

According to the power storage device of the ninth aspect of the present application, the contact resistance can be reduced, and thermal deformation due to the difference in the thermal expansion coefficients can be prevented.

According to the electricity storage device of the tenth aspect of the present application, by forming the inner insulating member with a resin material having a higher melting point than the inner layer, the thermal influence on the inner insulating member during heat sealing can be suppressed.

The power storage device according to the eleventh aspect of the present application is applicable to, for example, a Hybrid Electric Vehicle (HEV) or an Electric Vehicle (EV) in which several tens of the present power storage devices are connected in series and used to have a high voltage of 100V or more (e.g., 500V).

According to the method of manufacturing an electric storage device of the twelfth aspect of the present application, it is possible to easily provide an electric storage device in which a caulking pressure is applied via a plate-shaped external lead and an internal lead, so that damage due to local pressurization of an insulating member or an outer package is prevented, and an outer insulating member and/or an inner insulating member disposed on both surfaces of the outer package is pressed into a gap formed between a through hole of the outer package formed in advance to have a diameter larger than that of a through shaft and a through hole of a connection terminal by a uniform planar pressure, thereby ensuring reliable connection reliability and insulation reliability around the through shaft.

According to the method for manufacturing an electricity storage device of the thirteenth aspect of the present application, it is possible to easily realize the inner layer protection device that also serves as the inner insulating member, thereby omitting the additional step such as the bonding operation and preventing the direct contact between the metal member and the inner layer of the outer package.

Drawings

FIG. 1 is a plan view of a power storage device of the invention;

FIG. 2 is a sectional view of the power storage device taken along line X-X of FIG. 1;

FIG. 3 is a sectional view of the power storage device taken along the line Y-Y of FIG. 1;

fig. 4 is an explanatory diagram of the battery element 10;

FIG. 5 is a partial explanatory view of a portion near a through hole of a power storage device according to the present invention.

Description of the symbols

1 lithium ion accumulator

10 cell element

10a positive electrode

10b negative electrode

11a positive electrode collector

11b negative electrode collector

12a positive electrode active material

12b negative electrode active material

15 partition board

20 outer package

21a inner layer

21b metal layer

21c outer surface layer

23 Heat seal part

25 insulating tape

31 inner lead

31a positive electrode inner lead

31b negative electrode inner lead

32 external lead

32a positive electrode external lead

32b negative external lead

33 rivet

33B inner jaw part

33D step part

33S through shaft

33T outer jaw

41 inner side insulating member

43 outer insulating member

51a, 51b, 51c, 51d, 51e, 51f, 51g through hole

Detailed Description

Next, an embodiment of the power storage device of the present invention will be described.

Fig. 1 is a plan view of a power storage device of the present invention, fig. 2 is a cross-sectional view taken along line X-X of fig. 1, fig. 3 is a cross-sectional view taken along line Y-Y of fig. 1, fig. 4 is an explanatory view of a battery element 10, and fig. 5 is a partial explanatory view of the vicinity of a through hole of the power storage device. (although fig. 2, 3, and 5 show cross-sectional views and partial explanatory views of the positive electrode side, the negative electrode side is the same as the positive electrode side.)

As shown in fig. 1 to 4, a lithium ion battery 1, which is an example of the power storage device of the present invention, includes: a sheet-shaped battery element 10 formed by alternately stacking a plurality of sheet-shaped positive electrodes 10a and a plurality of sheet-shaped negative electrodes 10b with separators 15 interposed therebetween; a flexible exterior body 20 which accommodates the battery element 10 and an electrolyte solution, not shown, in a sealed state; a positive-electrode-side inner lead 31a connecting the positive electrodes 10a of the battery element 10 to each other inside the exterior body 20; a negative-electrode-side inner lead 31b connecting the negative electrodes 10b of the battery element 10; a positive-side outer lead 32a disposed outside the exterior body 20 corresponding to the positive-side inner lead 31a with the exterior body 20 interposed therebetween; a negative-side outer lead 32b disposed outside the outer package 20 corresponding to the negative-side inner lead, with the outer package 20 interposed therebetween; a pair of two rivets 33a (4 rivets in total)₁、33a₂(positive electrode side) and 33b₁、33b₂(negative electrode side) which penetrates the exterior body 20 in an airtight manner, one end side of which is connected to the inner leads 31a and 31b positioned inside the exterior body 20, and the other end side of which is connected to the outer leads 32a and 32b positioned outside the exterior body 20, respectively, so that the inner leads 31a and 31b and the outer leads 31a and 31b are connected to each otherAnd a connection terminal for electrically connecting the leads 32a and 32 b.

Further, an inner insulating member 41 and an outer insulating member 43 are interposed between the inner leads 31a and 31b and the exterior body 20 and between the outer leads 32a and 32b and the exterior body 20, and the inner insulating member 41 and the outer insulating member 43 are used for fixing the rivet 33a₁、33a₂、33b₁、33b₂The through holes of the outer package 20 that penetrate through the outer package 20 are sealed, and insulation between the surface of the outer package 20 and the inner leads 31a and 31b and the outer leads 32a and 32b is ensured.

Next, the details of each constituent element of the lithium ion secondary battery of the present invention having the above-described configuration will be described.

[ concerning the battery element 10 ]

As best shown in fig. 4, the battery element 10 is formed by alternately stacking a plurality of short-grid-shaped positive electrodes 10a and a plurality of short-grid-shaped negative electrodes 10b via a plurality of short-grid-shaped separators 15. Here, the positive electrode 10a is formed by laminating the positive electrode active material 12a on both surfaces of the positive electrode current collector 11 a. The positive electrode current collector 11a is made of aluminum, and the positive electrode active material 12a is made of a lithium cobaltate composite oxide (LCO). On the other hand, the negative electrode 10b is formed by laminating a negative electrode active material 12b on both surfaces of a negative electrode current collector 11 b. The negative electrode current collector 11b is made of copper, and the negative electrode active material 12b is made of a carbon material. The end portions 111a of the plurality of positive electrode current collectors 11a constituting the plurality of positive electrodes 10a and the end portions 111b of the plurality of negative electrode current collectors 11b constituting the plurality of negative electrodes 10b are laminated on the corresponding positive electrode inner lead 31a and negative electrode inner lead 31b, respectively, and are connected by ultrasonic welding or the like.

(other embodiments of the Battery element 10)

In the above embodiment, the battery element 10 has a stacked-sheet structure in which the short-grid-shaped positive electrode, negative electrode, and separator are stacked, but a wound-type structure in which long positive electrodes, negative electrodes, and separators are wound may be employed (for example, ends of the current collectors of the positive electrodes and negative electrodes are vertically drawn out along the winding axis, and the connection terminals of the above embodiment are electrically connected to the ends).

The battery element 10 is not particularly limited as long as it is used in an electric storage device such as a lithium ion battery, a lithium secondary battery, a polymer secondary battery, or an electric double layer capacitor.

The separator 15 is not particularly limited, and a conventionally known separator may be used. In addition, in the separator of the present invention, a solid electrolyte or a colloidal electrolyte having a function (function) as a separator may be used instead of the separator without being limited to the name. In addition, a separator containing an inorganic material may also be used.

As the positive electrode active material 12a, lithium manganate composite oxide (LMO) or lithium nickelate composite oxide (LNO) may be used in addition to lithium cobaltate composite oxide (LCO). In addition, ternary materials called LNMCO or binary materials called LMNO, LMCO, LNCO may also be used. It is also possible to use a material in which their main materials are mixed.

As a carbon material of the negative electrode active material 12b, graphite, hard carbon, or the like is used. In addition, a mixture of the main materials may be used.

[ concerning the outer package 20 ]

As shown in FIGS. 2 and 3, the outer package 20 of the present invention is formed of a laminated film having a three-layer structure including an inner surface layer 21a (having a thickness of 30 to 120 μm) made of polypropylene on the inner surface side, an intermediate layer 21b (having a thickness of 30 to 50 μm) made of aluminum foil or aluminum alloy foil in the middle, and an outer surface layer 21c (having a thickness of 20 to 40 μm) made of nylon on the outer surface side. Furthermore, the rivet 33a₁、33a₂The diameter of the through hole of the outer package 20 is set to be larger than the diameter of the through shaft of the rivet.

The exterior body 20 is formed by laminating upper and lower cup-shaped laminate films, and then heat-sealing (heat-welding) the peripheral heat-sealed portions 23 to join the inner surfaces 21a to each other, thereby sealing the battery element 10 inside. The laminated film is lightweight and has excellent flexibility, and has excellent barrier function and sealing property against moisture and the like from the outside.

As shown in fig. 1 and 2, in order to prevent short-circuiting due to contact between the outer lead 32a and the intermediate layer (metal layer) 21b of the outer package 20 at the edge of the outer package 20 near the outer leads 32a and 32b, an insulating tape 25 (e.g., カプトン (registered trademark)) made of a heat-resistant and electrically insulating polyamide resin or the like is provided so as to extend over the heat-seal portion 23 in the thickness direction of the outer package 20.

(other embodiment of outer package 20)

In the above embodiment, the outer package 20 is formed of a laminated film having a three-layer structure, but the outer package 20 may be formed such that most (major plane) of the outer package 20 is a metal layer and only the heat-sealable portion 23 has the heat-sealable inner surface layer 21 a. The material of the metal layer 21b may be any metal having a barrier property against moisture or the like and excellent flexibility and strength, and may be stainless steel, nickel or a nickel alloy, copper or a copper alloy, iron or an iron alloy, or the like. The metal layer 21b may be formed in a foil shape (thin plate shape) as a preform, or may be formed in a thin film or by plating. The metal layer 21b may also be made into a multilayer structure. Alternatively, the inner surface layer 21a or the outer surface layer 21c may be formed in a multilayer structure.

The material of the back surface layer 21a may be a thermoplastic resin having excellent electrolyte resistance and heat sealability, and may be a resin such as polyethylene, polystyrene, polyamide, ionomer, or the like. The material of the outer layer 21c may be any insulating resin having excellent electrical insulation properties, and may be a resin such as Polyester (PET) or other polyamide.

In the above embodiment, the two laminated films are stacked and then the peripheral heat-sealed portions 23 are heat-welded to seal the battery element 10 inside, but as a method of sealing the laminated films, one laminated film may be folded into two and then the peripheral heat-sealed portions 23 in the three sides may be heat-welded to each other, or one laminated film may be formed into a cylindrical shape and then the openings (heat-sealed portions) in both sides may be heat-welded to each other. In the case of forming the tube, the position of the heat-sealed portion (band-shaped portion) other than the openings on both sides may be arbitrarily set.

[ concerning the inner leads 31a, 31b, the outer leads 32a, 32b and the rivet 33a ]₁～33b₂〕

As shown in fig. 1 to 3, the plate-like inner leads 31a are electrically connected to the battery element 10 inside the outer package 20, and the plate-like outer leads 32a electrically connected to the outside are disposed opposite to the inner leads 31a with the outer package 20 interposed therebetween. The inner lead 31a and the outer lead 32a are connected by a rivet 33a₁、33a₂And performing mechanical and electrical connection. Here, the rivet 33a₁、33a₂Comprising: a penetration shaft 33S penetrating the inner lead 31a, the outer lead 32a, and the like; an outer flange portion 33T formed integrally with the through shaft 33S in advance at one end portion of the through shaft 33S and disposed outside the outer package 20; an inner flange 33B newly formed at the other end of the through shaft 33S by caulking and disposed inside the outer package 20.

The positive-electrode-side inner lead 31a is a thick plate-like member, and is set to be equal to or larger than the thickness of the end portions 111a of the plurality of positive electrode collectors 11a (for example, 0.3 to 3 mm). The inner lead 31a and the positive electrode current collector 11a are made of aluminum or an aluminum alloy of the same material. On the other hand, the negative-side inner lead 31b is a thick plate-like member, and is set to be equal to or larger than the thickness of the end portions 111b of the plurality of negative electrode current collectors 11b (for example, 0.3 to 3 mm). The inner lead 31b and the negative electrode current collector 11b are made of copper or a copper alloy of the same material. The inner leads 31a and 31b are disposed at both ends of the battery element 10 in the longitudinal direction and in parallel with the width direction, together with the rectangular battery element 10 in a plan view, and are housed in the exterior body 20, and the end portions 111a of the plurality of positive electrode current collectors 11a and the end portions 111b of the negative electrode current collectors 11b corresponding to the battery element 10 are connected by ultrasonic welding or the like, respectively.

On the other hand, the external lead 32a on the positive electrode side is a thick plate-like member and is set to be equal to (for example, 0.3 to 3mm) the thickness of the internal lead 31 a. In addition, the outer lead 32a is formed of copper or a copper alloy. Copper or copper alloy is preferable in terms of reduction in contact resistance in use at high voltage. Similarly, the outer lead 32b on the negative electrode side is a thick plate-like member and is set to be equal to (for example, 0.3 to 3mm) the thickness of the inner lead 31 b. The external lead 32b and the negative electrode current collector 11b are made of copper or a copper alloy of the same material. The positive-side external lead 32a (right side in fig. 1) and the negative-side external lead 32b (left side in fig. 1) are disposed outside the outer package 20 so as to face the corresponding positive-side internal lead 31a and the corresponding negative-side internal lead 31b with the outer package 20 interposed therebetween. That is, the outer leads 32a and 32b are not drawn to the outside from the four heat-sealed portions 23 of the outer package 20, but are drawn to the outside so as to face the corresponding inner leads 31a and 31b and extend along the outer surface of the outer package 20.

The inner lead 31a and the outer lead 32a have the same L dimension (dimension in the longitudinal direction) and are substantially the same as the W dimension (dimension in the width direction) of the battery element 10. As shown in fig. 3, the W size of the inner lead 31a and the outer lead 32a is substantially the same. The inner lead 31a and the outer lead 32a have the same T-dimension (height-direction dimension).

Rivet 33a₁、33a₂The through shaft 33S and the outer flange 33T are integrally formed in advance. The outer surface of the outer collar 33T is flat, and the thickness of the collar is uniform. On the other hand, the inner collar 33B is formed by caulking the distal end of the through shaft 33S to crush a part of the through shaft 33S, and has a non-uniform thickness and a rough surface roughness on the outer surface compared to the outer collar 33T. At this time, the diameter of the through shaft 33S is larger than that before caulking, and a stepped portion 33D having a different diameter is formed. By placing the external lead 32a on the stepped portion 33D, reliable engagement with the external lead 32a can be achievedThis contributes to a reduction in contact resistance. The inner lead 31a may be engaged with the step portion 33D by a pressing method.

Rivet 33a₁、33a₂In addition to the through shaft 33S and the outer flange 33T being integrally formed in advance, the inner flange 33B is also integrally formed at the time of caulking, and thus, compared with a coupling structure by a bolt and a nut or an adhesive structure by a resin or the like, for example, the penetration of moisture from the outside can be more effectively prevented by the flange integrally formed with the through shaft. Thereby, the rivet 33a can be realized₁、33a₂Excellent sealing performance and conductivity.

Rivet 33a on the positive electrode side₁、33a₂Is made of aluminum or aluminum alloy of the same material as the positive-side inner lead 31a, and a negative-side rivet 33b₁、33b₂Is copper or a copper alloy of the same material as the negative-electrode-side inner lead 31b and the outer lead 32 b. For the inner leads 31a, 31b and the rivet 33a₁、33a₂By using the same material, contact resistance can be reduced and thermal deformation due to a difference in thermal expansion coefficient can be prevented.

Further, the rivet 33a on the positive electrode side₁、33a₂And a rivet 33b on the negative electrode side₁、33b₂A plurality of external leads 32a (internal leads 31a) on the positive electrode side and a plurality of external leads 32b (internal leads 31b) on the negative electrode side are provided (in this example, two positive electrode sides 33a are provided, respectively)₁、33a₂And a negative electrode side 33b₁、33b₂). Specifically, as shown in fig. 1 and 2, the substantially central portion in the longitudinal direction of the positive-side inner lead 31a and the end portion in the longitudinal direction of the positive-side outer lead 32a (left end portion of the outer lead 32a in fig. 2) are formed by the positive-side rivet 33a₁And the end portion in the longitudinal direction of the internal lead 31a on the positive electrode side (the right end portion of the internal lead 31a in fig. 2) and the substantially central portion in the longitudinal direction of the external lead 32a on the positive electrode side are connected by the rivet 33a on the positive electrode side₂To be connected. Similarly, the substantially central portion of the inner lead 31b on the negative electrode side in the longitudinal direction and the outer portion on the negative electrode sideThe end of the lead wire 32b in the longitudinal direction is formed by a rivet 33b on the negative side₁The end part of the inner lead 31b on the negative side in the longitudinal direction and the outer lead 32b on the negative side in the longitudinal direction are connected by the rivet 33b on the negative side₂To be connected. This improves the connection reliability between the inner leads 31a (31b) and the outer leads 32a (32 b). In addition, in the case of using the plate-shaped external lead described above in response to a request called a large capacity or high voltage, it is preferable to connect the external lead by a plurality of rivets, but since the inner insulating member or the outer insulating member described later is a single member as compared with a configuration in which an insulating member is wound around each of a plurality of through-shafts, for example, the number of parts is reduced, an adhesion operation is omitted, and a positioning operation is simplified, it is possible to achieve a significant improvement in productivity and a reduction in cost.

(inner leads 31a, 31b, outer leads 32a, 32b and rivet 33 a)₁～33b₂Other embodiments of the invention

In the above embodiment, the material of the positive-side inner lead 31a and the material of the positive-side outer lead 32a are different, but the same material may be used. When the outer lead 32a is made of aluminum or an aluminum alloy in the same manner as the inner lead 31a, it is advantageous for weight reduction. The inner lead 31b and the outer lead 32b on the negative electrode side are made of the same material, but may be made of different materials. Nickel plating or tin plating may be applied to the copper or copper alloy of the negative-side outer lead 32 b.

The relationship between the L, W, and T dimensions of the inner leads 31a, 31b and the outer leads 32a, 32b is not limited to the above embodiment, and may be set arbitrarily. The relationship between the L dimension of the inner leads 31a and 31b and the W dimension of the battery element 10 can be set arbitrarily.

For example, when the materials of the inner leads 31a and 31b and the outer leads 32a and 32b are different from each other, the L size, the W size, and the T size may be different between the inner lead 31 and the outer lead 32, and may be set as appropriate depending on the allowable current of the materials of the inner lead 31 and the outer lead 32.

The shape of the outer leads 32a, 32b can be set in particular to a free shape. The shape is not limited to the linear shape of the above embodiment, and the protruding end (the through hole 51g side in fig. 1) may be bent into a key shape, bent into an R shape, or formed into two strands. The L, W, and T dimensions of the outer leads 32a and 32b need not be uniform throughout the entire structure, and may be, for example, thin portions or thick portions.

The lead-out directions of the external leads 32a and 32b are not limited to the lead-out directions parallel to each other in the width direction of the outer package 20 as in the above-described embodiment, and may be, for example, the lead-out directions aligned in the longitudinal direction (the left-right direction in fig. 1) of the outer package 20. The external lead 32a on the positive electrode side and the external lead 32b on the negative electrode side are not limited to being drawn in the same direction, and may be drawn in opposite directions (vertical direction in fig. 1) or asymmetrical directions.

The types of rivets of the above embodiments include: solid rivets, full blind rivets, semi-blind rivets, open rivets, compression rivets, blind rivets, and the like.

Further, the inner leads 31a, 31b, the outer leads 32a, 32b, and the rivet 33a₁～33b₂Or may be integrally formed. For example, the through shaft 33S may be integrally formed on one of the inner lead 31a and the outer lead 32a, a through hole into which the through shaft 33S is fitted may be provided on the other side, and the fitted protrusion may be swaged to form a collar (the same applies to the inner lead 31b and the outer lead 32 b).

Further, as the connection terminal, a device such as a screw or a bolt-nut fixing may be used, but since the sealing property from the outside is poor, in the case of using them, at least the outer flange portion 33T must be formed integrally with the through shaft 33S.

Rivet 33a of the above embodiment₁～33b₂Two positive electrodes and two negative electrodes are provided, respectively, but the number of the positive electrodes and the negative electrodes is limitedAnd is not particularly limited. However, in order to prevent the rotation of the connected external leads 32a and 32b, at least two or more are preferable.

The cross-sectional shape of the through shaft 33S may be set arbitrarily. As long as the sectional shape is, for example, an ellipse or a polygon, it is effective for preventing rotation. The planar shape of the outer flange 33T can be set arbitrarily. The cross-sectional shape of the through shaft 33S may be such that the rotation is prevented as described above, and may be only at substantially the center of each of the inner leads 31a and 31b (the rivet 33a in fig. 1)₁、33b₁Position of) a rivet 33a is provided₁～33b₂The composition of (1). In this case, the rivet (rivet 33a of fig. 1) on the side of connection with the outside can be prevented from coming close to₂、33b₂) Is concentrated.

[ concerning insulating parts ]

As shown in fig. 1 to 3, an inner insulating member 41 made of the same material (polypropylene in this example) as the inner surface layer 21a of the outer package 20 and having a thickness of 100 to 350 μm is interposed between the inner surface of the outer package 20 and the inner lead 31a, and an outer insulating member 43 made of the same material (polypropylene in this example) as the inner insulating member 41 and having a thickness of 100 to 350 μm is interposed between the outer surface of the outer package 20 and the outer lead 32 a. The outer insulating member 43 may be formed of the same material as the outer surface layer 21c of the outer package 20.

As will be described in detail later, the rivet 33a is used₁～33b₂When the parts are connected, the inner insulating member 41 and the outer insulating member 43 are fixed to the metal layer 21b and the rivet 33a of the exterior body 20₁～33b₂The through shafts 33S are inserted (press-fitted) so as to be closely contacted with each other. Thus, the sealing performance and the insulating performance around the rivet are improved by a simple structure.

As shown in fig. 3, the inner insulating member 41 of the present embodiment is formed so that its cross section is substantially コ characters, and thus the inner insulating member 41 also serves as a back surface layer protection device for protecting the back surface layer 21a of the outer package 20 from mechanical damage. More specifically, the surface of the inner lead 31a is covered with a portion (corresponding to an upper portion of a substantially コ -shaped shape) extending along the inner surface layer 21a (the surface of the inner lead 31a) of the outer package body 20 from the left side to the right side (outer side) in fig. 3, and a portion (corresponding to a side portion of a substantially コ -shaped shape) folded back by about 90 degrees from this position to the lower side is covered with a portion (corresponding to a lower portion of a substantially コ -shaped shape) folded back by about 90 degrees from the right side to the left side (inner side) so as to extend along the surface of the end portion 311a of the inner lead 31a and the end portion 111a of the current collector 11a close to the inner surface layer 21a of the outer package body 20, and the surface of the inner collar 33B (the negative electrode side) is covered with.

Although a slight gap is formed between end 111a of current collector 11 and inner insulating member 41 in fig. 3, inner insulating member 41 may be formed so as to follow (completely adhere to) the surface of end 311a of inner lead 31a or end 111a of current collector 11. The inner insulating member 41 covers the end 311a of the inner lead 31a and the end 111a of the current collector 11a from the side of the paper surface of fig. 3 inward, that is, in the longitudinal direction of the end 311a of the inner lead 31 a.

In general, in the exterior body 20 having a multilayer structure including the inner surface layer 21a formed of a thermoplastic resin (polypropylene in this example) and the metal layer 21B on the outer side thereof in a heat-sealable manner, when the inner surface layer 21a comes into contact with metal members (for example, the inner lead 31a, the positive electrode collector 11a, the inner collar portion 33B, and the like) inside the exterior body 20, the inner surface layer 21a is damaged, and the metal layer 21B may be exposed. The exposure of the metal layer 21b following such damage of the back surface layer 21a may cause an internal short circuit due to subsequent contact with the metal member.

Therefore, as described above, the inner insulating member 41 of the present embodiment is formed to have a substantially コ -shaped cross section so as to be folded back near the end portion of the inner lead 31a close to the inner surface layer 21a of the outer package 20 and cover the end portion 311a of the inner lead 31a, the end portion 111a of the current collector 11a, and the inner collar portion 33B, whereby the inner insulating member 41 also serves as an inner surface layer protection device for preventing damage to the inner surface layer 21 a. This prevents the damage of the back surface layer 21a due to the contact between the back surface layer 21a and the metal member with a simple structure, thereby preventing a short circuit due to the contact with the metal layer 21 b. Further, since the inner insulating member 41 is commonly used (dual purpose) and the inner surface layer 21a of the outer package 20 is protected by folding back only the inner insulating member 41, the number of parts can be reduced and the additional work steps such as bonding work can be omitted as compared with a configuration in which such a protective member is separately provided, which contributes to cost reduction and productivity improvement.

As shown in fig. 2 and 3, the inner insulating member 41 has an L-size equal to or greater than the L-size of the inner lead 31a, and has a W-size equal to or greater than the W-size of the inner lead 31 a.

On the other hand, the outer insulating member 43 has an L dimension such that the outer lead 32a does not contact the principal plane of the outer surface layer 21c of the outer package 20 as much as possible, and has a W dimension equal to that of the inner insulating member 41.

(other embodiments of insulating Member)

The inner insulating member 41 may be a thermoplastic resin having excellent electrolyte resistance and heat sealability, and may be a resin such as polyethylene, polystyrene, polyamide, ionomer, or the like. In order to avoid the influence of heat during heat sealing, it is preferable that the resin material has a higher melting point than the back surface layer 21a of the outer package 20. The inner insulating member 41 and the outer insulating member 43 may be made of different materials, and may have different widths and thicknesses.

In the present embodiment, the inner insulating member 41 is formed to have a substantially コ -shaped cross section, but may be configured as follows: by forming the outer package body 20 so as to have a substantially L-shaped cross section, the surface of the inner lead 31a is covered with a portion (corresponding to the substantially L-shaped upper portion) along the inner surface layer 21a (the surface of the inner lead 31a) of the outer package body 20, and the portion (corresponding to the substantially L-shaped side portion) folded back by about 90 degrees from there to the lower side is covered (without covering the inner collar portion 33B) so as to follow the surface of the end portion 311a of the inner lead 31a and the end portion 111a of the positive electrode collector 11a close to the inner surface layer 21a of the outer package body 20. Even if the cross section is approximately コ, the following configuration may be adopted: the surface of the inner lead 31a is covered with a portion (corresponding to an upper portion of a substantially コ -letter shape) along the inner surface layer 21a (the surface of the inner lead 31a) of the exterior body 20, and the surface of the inner collar 33B is covered with a portion (corresponding to a lower portion of a substantially コ -letter shape) which is folded back by about 90 degrees (corresponding to a side portion of a substantially コ -letter shape) from the lower side thereof and is further folded back by about 90 degrees (corresponding to a lower portion of a substantially コ -letter shape) (the surface of the end portion 311a of the inner lead 31a and the end portion 111a of the positive electrode collector 11a are not covered. The surface or end portion 311a of the inner lead 31a and the inner flange portion 33B need not be completely covered with the inner insulating member 41, but may function as an inner surface layer protection device for protecting the inner surface layer 21a of the outer package 20 from mechanical damage.

In the present embodiment, the inner insulating member 41 also serves as a back surface layer protection device for protecting the back surface layer 21a of the outer package body 20 from mechanical damage, but it is needless to say that such a back surface layer protection device may be separately provided as an end portion cover or a flange portion cover. Further, the inner surface layer protection device may be configured to prevent the inner surface layer 21a from being damaged by contact by performing chamfering, curving, surface treatment, or the like on each corner portion of the end portion 311a of the inner lead 31a, the end portion 111a of the positive electrode collector 11a, and the surface of the inner collar portion 33B.

The outer insulating member 43 may be an insulating resin having excellent electrical insulating properties, and may be a resin such as polyester or other polyamide. The inner insulating member 41 and the outer insulating member 43 may be made of different materials. The inner insulating member 41 and the outer insulating member 43 may be made of the same material as the inner surface layer 21a and the outer surface layer 21c of the laminated film, respectively, but may be made of different materials.

The inner insulating member 41 or the outer insulating member 43 may be made of an insulating resin as described above, but may be made of an elastic material such as natural rubber or synthetic rubber. Thereby achieving stress relaxation around the rivet.

Further, a bush material may be implanted into the outer flange portion 33T of the above embodiment, and an insulating resin may be formed around the penetrating shaft 33S at the time of caulking. Further, an insulating resin such as silicone resin may be applied to the surface of the through shaft 33S in advance.

[ production method ]

The method for manufacturing the lithium ion secondary battery 1, which is the power storage device of the present invention, is not particularly limited, and for example, the lithium ion secondary battery can be manufactured in the following procedure. Since the same connection method is used for both the positive electrode side and the negative electrode side, a general reference numeral (for example, current collector 11) is used for the following symbols of the respective members.

(1) First, as shown in fig. 5, corresponding through holes (51a to 51e) are formed at predetermined positions where the inner lead 31, the inner insulating member 41, the outer package 20, the outer insulating member 43, and the outer lead 32 of the battery element 10 are connected. Further, a through hole 51g is formed at the tip of the external lead 32 to be connectable to an external connection terminal or a battery pack.

(2) Next, the battery element 10 and the inner lead 31 are connected. Specifically, from the viewpoint of stacking end portions 111 of a plurality of current collectors 11 and protecting current collectors 11 from the mechanical damage during caulking through shaft 33S, through-holes 51f are formed in end portions 111 of current collectors 11, and each through-hole 51f has a diameter that maintains an extra space to the extent that the through-hole does not contact an inner collar 33b described later. The through hole 51a of the inner lead 31 and the through hole 51f of the end 111 of the current collector 11 are substantially aligned, and the end 111 of the current collector 11 and the inner lead 31 are ultrasonically welded by a jig, not shown.

Here, the through hole 51a of the inner lead 31, the through hole 51b of the inner insulating member 41, the through hole 51d of the outer insulating member 43, and the through hole 51e of the outer lead 32 are formed to have a diameter equal to the diameter of the through shaft 33S of the rivet 33, whereas the through hole 51c of the outer package 20 is formed in advance to have a diameter larger than the diameter of the through shaft 33S of the rivet 33. By forming the diameter of the through hole 51c of the outer package 20 to be larger than the diameter of the through shaft 33S of the rivet 33 in this way, a gap can be formed between the through shaft 33S and the outer package 20 (particularly, the metal layer 21b) when the through shaft 33S is inserted. The diameter of the through hole 51c of the outer package 20 is preferably smaller than the diameter of the outer flange 33T of the rivet 33 in order to securely hold the outer package 20. The inner insulating member 41 is formed in advance to have a predetermined length so as to cover the end 311 of the inner lead 31, the end 111 of the current collector 11, and the surface of the inner collar 33B.

In addition, although the through holes 51f and 51a may be provided in the end 111 of the current collector 11 and the inner lead 31, respectively, and then the both may be connected by ultrasonic welding as described above, from the viewpoint of simplifying the manufacturing process, the through holes 51a (51f) penetrating the inner lead 31 and the end 111 of the current collector 11 may be integrally formed at the same time after the battery element 10 and the inner lead 31 are ultrasonically welded.

(3) Next, the battery element 10 provided with the inner leads 31 is housed inside the upper and lower cup-shaped exterior bodies 20.

(4) Next, the inner insulating member 41, the outer package 20, the outer insulating member 43, and the outer leads 32 are disposed on the inner leads 31 by aligning the through holes 51a, 51b, 51c, 51d, and 51e, respectively.

(5) Thereafter, a rivet 33 having an outer flange 33T and a penetrating shaft 33S is prepared, the outer flange 33T is made to be an outer side, and the penetrating shaft 33S is inserted through the through holes 51e, 51d, 51c, 51b, and 51a in this order of the outer lead 32, the outer insulating member 43, the outer package 20, the inner insulating member 41, and the inner lead 31.

(6) Next, the protruding distal end portion of the through shaft 33S is pressed (swaged) by a method such as a striking, hydraulic pressure, or pneumatic pressure using a jig (not shown), whereby the distal end portion of the through shaft 33S is crushed, and the inner flange portion 33B is newly formed.

When the inner lead 31 and the outer lead 32 are fixed by caulking with the rivet 33 in this way, the inner insulating member 41, the outer package 20, and the outer insulating member 43 are sandwiched between the two plate-like inner lead 31 and outer lead 32 by surface pressure, whereby the through hole 51a of the outer package 20 through which the rivet 33 penetrates is hermetically sealed, and the inner lead 31 and the outer lead 32 are electrically connected by the rivet 33. Further, since the diameters of the through holes 51b and 51d of the inner insulating member 41 and the outer insulating member 43 are set to be substantially equal to the diameter of the through shaft 33S and the diameter of the through hole 51a of the outer package 20 is set to be larger than the diameter of the through shaft 33S, the inner insulating member 41 and/or the outer insulating member 43 can be pressed into the gap formed between the through shaft 33S of the rivet 33 and the outer package 20 by the caulking pressure at the time of rivet connection, and the insulation from the metal layer 21b of the outer package 20 can be stably secured for a long period of time.

More specifically, the inner insulating member 41 and the outer insulating member 43 are disposed inside and outside the outer package 20, respectively, before caulking, but the inner lead 31 is deformed in a direction approaching the outer lead 32 (both the inner lead 31 and the outer lead 32 may be deformed) at the time of caulking, and therefore the inner insulating member 41 and the outer insulating member 43 are also deformed in a direction approaching each other and are brought into close contact with each other. That is, the deformation of the inner lead 31 and/or the outer lead 32 at the time of caulking promotes the press-fitting and filling of the through hole 51c of the inner insulating member 41 and/or the outer insulating member 43. This makes it possible to reliably insert the insulating members 41 and 43 between the metal layer 21b of the outer package 20 and the through-shaft 33S with a simple configuration without precisely positioning the outer package 20 and the rivet 33.

Further, since the inner insulating member 41 and the outer insulating member 43 are pressed in by planar pressing via the plate-like inner lead 31 and the plate-like outer lead 32, mechanical damage such as damage to the inner insulating member 41, the outer insulating member 43, and the outer package 20 due to local pressing can be prevented, and the respective through holes can be prevented from becoming excessively large, thereby ensuring good sealing performance.

Further, since the inner insulating member 41 and/or the outer insulating member 43 also serve as an insulating member inserted around the through shaft 33S, a step of filling a space between the metal layer 21b of the outer package 20 and the through shaft 33S with another insulating member in advance or filling another insulating member after connection can be omitted, which contributes to improvement in workability and cost reduction.

(7) Then, inside the two upper and lower cup-formed outer packages 20, the inner insulating member 41 is folded back at the end portions of the inner leads 31 (near the sealing portions 23 of the outer packages 20), and the end portions 311 of the inner leads 31, the end portions 111 of the current collectors 11, and the inner collar portions 33B are covered with the inner insulating member 41. This makes it possible to realize a simple inner layer protection device that prevents mechanical damage to the inner layer 21a of the outer body 20 due to contact between the inner layer 21a and the metal member, by using (utilizing) the inner insulating member 41 in combination.

(8) Next, the heat-sealed portions 23 on the periphery of the outer package 20 are heat-welded, the inner surface layers 21a are heat-sealed to each other, and the entire package is sealed by vacuum suction.

(9) Next, an opening is formed by partially cutting the heat-sealed portion 23 of the outer package 20, and after injecting an electrolyte solution into the outer package 20 through the opening, the outer package is temporarily sealed.

(10) Next, initial charging is performed, and after evacuation, the inside of the cut heat-sealed portion 23 is heat-welded again to close the opening portion, thereby sealing the whole.

(other embodiment of the production method)

The diameter of the through hole 51c of the outer package 20 is preferably the same as or smaller than the diameter of the outer flange 33T of the rivet 33. If the diameter of the through hole 51c is made too large than the diameter of the outer flange 33T, the sealing reliability may be lowered. Further, the diameter of the through hole 51b of the inner insulating member 41 and the diameter of the through hole 51d of the outer insulating member 43 are formed to be slightly smaller than the diameter of the through shaft 33S of the rivet 33, and the inner insulating member 41 and/or the outer insulating member 43 are likely to come into close contact with the through shaft 33S, but if too small, there is a possibility that undesired deformation such as bending or lifting of the inner insulating member 41 and/or the outer insulating member 43 may occur. The diameter of the through hole 51b of the inner insulating member 41 and the diameter of the through hole 51d of the outer insulating member 43 may be different. Since the inner insulating member 41 close to the newly formed inner flange 33B is easily deformed by caulking, the diameter of the through hole 51B may be formed to be slightly smaller than the diameter of the through hole 51d in consideration of the amount of deformation.

The following examples show the insulation performance of the electric storage device formed as described above, compared with the electric storage device having a conventional configuration. In addition, in the case of verification, the example (comparative example 1) was used in which the tip portion of the inner lead was protruded to the outside from the heat-sealed portion 23 of the exterior body 20, and the portion protruded to the outside was used as the outer lead; in the connection structure using the rivet 33, the diameter of the through hole 51c of the outer package 20 is set to be substantially equal to the diameter of the through shaft 33S of the rivet 33 (comparative example 2), and the respective insulation performances are measured and compared and verified.

Example 1

The specifications of each constituent element used for the verification are as follows.

Battery element 10: 300mm (L size) × 120mm (W size) × 5mm (T size)

Inner lead 31: 100mm (L size) × 15mm (W size) × 1.5mm (T size), aluminum, diameter of through-hole 51 a: 4mm

External lead 32: 100mm (L size) × 15mm (W size) × 1.5mm (T size), aluminum or copper, diameter of through-hole 51 e: 4mm

Rivet 33: diameter of the through shaft 33S 4mm Φ × length 6mm, diameter of the rivet made of aluminum or copper, and diameter of the outer flange 33T: 8mm

Inner insulating member 41, outer insulating member 43: diameter of each through hole 51b, 51d made of polypropylene having a thickness of 250 μm: 4mm

Outer package 20: 320mm (L size). times.135 mm (W size). times.7 mm (T size) aluminum laminate (inner surface layer 21 a: polypropylene having a thickness of 80 μm, metal layer 21 b: aluminum foil having a thickness of 40 μm, outer surface layer: nylon having a thickness of 25 μm), diameter of through-hole 51 c: 6mm

Electrolyte solution: LiPF6 was dissolved as a salt in 1mol/l in Ethylene Carbonate (EC) and diethyl carbonate (DEC)

Under the above conditions, 10 lithium ion secondary batteries having a battery capacity of 10Ah and a voltage of 4.2V, which were used in example 1, were produced. The insulation resistance value when a voltage of 100V was applied for 5 seconds and the insulation resistance value when a voltage of 500V was applied for 5 seconds were measured for each of 5 lithium ion batteries grouped by using a commercially available insulation resistance meter (2000 M.OMEGA.was measured at 100V; 4000 M.OMEGA.was measured at 500V).

Similarly, 5 lithium ion secondary batteries having a battery capacity of 10Ah and a voltage of 4.2V used in comparative example 1 and comparative example 2 were prepared, and the insulation resistance values when a voltage of 100V was applied for 5 seconds were measured. Table 1 shows the results of these measurements. In comparative examples 1 and 2, the insulation resistance value at the time of applying a voltage of 100V for 5 seconds was already small, and therefore, the measurement of the insulation resistance value at the time of applying a voltage of 500V for 5 seconds was not performed.

(Table 1)

As is clear from table 1, the lithium ion secondary battery of example 1 of the present invention has very excellent insulation performance at an insulation resistance value when a voltage of 100V is applied for 5 seconds, as compared with the lithium ion secondary batteries of comparative examples 1 and 2 having conventional structures. In addition, the lithium ion secondary battery of example 1 exhibited a sufficiently high insulation resistance value as an insulation performance when a voltage of 500V was applied for 5 seconds. As described above, according to the lithium ion secondary battery (example 1) of the present invention, it was confirmed that excellent insulation reliability and connection reliability were stably obtained with a simple configuration.

Industrial applicability

The power storage device of the present invention is suitable for use in automobiles, motorcycles, and the like with severe vibration. That is, in the structure disclosed in the conventional example of patent document 1 in which the connection terminal is protruded from the heat-sealed portion of the exterior body that has been thermally welded (in other words, the structure in which the connection terminal is sandwiched by chemically bonding the exterior bodies), the battery element and the connection terminal are also vibrated vigorously by the external violent vibration, and the sealability of the heat-sealed portion may be degraded.

On the other hand, in the electric storage device according to the present invention, since the plate-shaped lead terminals and the connection terminals having the shaft portions and the collar portions are mechanically and electrically joined to each other, and the connection terminals sandwich the exterior body via the plate-shaped lead terminals, the exterior body can be strongly held between the lead terminals and the connection terminals even when the exterior body is strongly vibrated from the outside, and high sealing performance can be maintained and high insulation performance can be maintained with a simple configuration. Therefore, the voltage regulator is suitable for use under high voltage (for example, 100V or more used under 500-1000V).

Claims (13)

1. An electrical storage device, comprising: a battery element housed in an exterior body having at least a metal layer; a plate-shaped inner lead connected to the battery element inside the outer package; a plate-shaped external lead arranged outside the outer package body so as to face the internal lead; a connection terminal electrically connecting the inner lead and the outer lead; an inner insulating member provided between the outer package and the inner lead along an inner surface of the outer package; an outer insulating member provided between the outer package and an outer lead along an outer surface of the outer package so as to face the inner insulating member,

the connection terminal has a through shaft through which the external lead, the external insulating member, the outer package, the internal insulating member and the internal lead are respectively passed, and flanges integrally formed at both end portions of the through shaft, wherein the flanges at both end portions of the connection terminal press and hold the external insulating member, the outer package and the internal insulating member via the plate-shaped external lead and the internal lead, and press the external insulating member or the internal insulating member between the through shaft of the connection terminal and the metal layer of the outer package, and the external insulating member or the internal insulating member is pressed and held between the through shaft and the metal layer of the outer package

The outer package is a multilayered outer package having a heat-sealable inner surface layer made of a thermoplastic resin on the inner surface thereof, the inner insulating member covers at least a part of any one of the battery element, the internal lead, and the connection terminal, thereby serving also as a protective device for the inner surface layer to prevent damage to the inner surface layer of the multilayered outer package, and the inner insulating member covers an end portion of the internal lead close to the inner surface layer of the multilayered outer package in the longitudinal direction of the internal lead.

2. An electrical storage device, comprising: a battery element housed in an exterior body having at least a metal layer; a plate-shaped inner lead connected to the battery element inside the outer package; a plate-shaped external lead arranged outside the outer package body so as to face the internal lead; a connection terminal electrically connecting the inner lead and the outer lead; an inner insulating member provided between the outer package and the inner lead along an inner surface of the outer package; an outer insulating member provided between the outer package and an outer lead along an outer surface of the outer package so as to face the inner insulating member,

the connection terminal has a through shaft through which the external lead, the external insulating member, the outer package, the internal insulating member, and the internal lead are respectively passed, and flanges integrally formed at both end portions of the through shaft, wherein the flanges at both end portions of the connection terminal press and hold the external insulating member, the outer package, and the internal insulating member via the plate-shaped external lead and the internal lead, and press and hold the external insulating member and the internal insulating member between the through shaft of the connection terminal and the metal layer of the outer package, and the external insulating member and the internal insulating member are pressed and held between the through shaft of the connection terminal and the metal layer of the outer

The outer package is a multilayered outer package having a heat-sealable inner surface layer made of a thermoplastic resin on the inner surface thereof, the inner insulating member covers at least a part of any one of the battery element, the internal lead, and the connection terminal, thereby serving also as a protective device for the inner surface layer to prevent damage to the inner surface layer of the multilayered outer package, and the inner insulating member covers an end portion of the internal lead close to the inner surface layer of the multilayered outer package in the longitudinal direction of the internal lead.

3. The power storage device according to claim 1 or 2, wherein the diameter of each through hole of the outer insulating member and the inner insulating member through which the through shaft of the connection terminal penetrates is formed to be substantially equal to the diameter of the through shaft, and the diameter of the through hole of the outer package through which the through shaft of the connection terminal penetrates is formed to be larger than the diameter of the through shaft in advance.

4. The power storage device according to claim 1 or 2, wherein the inner insulating member further covers a flange portion of the connection terminal near the inner surface layer of the outer package in a plurality of layers.

5. The power storage device according to claim 4, wherein the inner insulating member is formed in a substantially コ -shaped cross section by a portion along an inner surface layer of the outer package, a portion covering an end portion of the inner lead, and a portion covering a flange portion of the connection terminal.

6. The power storage device according to claim 1 or 2, wherein a plurality of the connection terminals are provided for the respective plate-shaped outer leads and inner leads.

7. The power storage device according to claim 1 or 2, wherein the connection terminals are rivets that are respectively coupled to the corresponding plate-shaped external lead and internal lead.

8. The power storage device according to claim 1 or 2, wherein the connection terminal is formed of at least the same material as that of the inner lead.

9. The power storage device according to claim 1 or 2, wherein the inside insulating member is formed of polypropylene, polyethylene, polystyrene, polyamide, or ionomer having a higher melting point than the inside surface layer that is heat-sealable.

10. The electrical storage device according to claim 1 or 2, characterized in that the electrical storage device is a lithium-ion battery used at a high voltage of 100V or more.

11. A method for manufacturing an electricity storage device, the electricity storage device comprising: a battery element housed in an exterior body having at least a metal layer; a plate-shaped inner lead connected to the battery element inside the outer package; a plate-shaped external lead arranged outside the outer package body so as to face the internal lead; a connection terminal electrically connecting the inner lead and the outer lead; an inner insulating member provided between the outer package and the inner lead along an inner surface of the outer package; an outer insulating member provided between the outer package and an outer lead along an outer surface of the outer package so as to face the inner insulating member,

a connection terminal having a through shaft and a flange formed in advance at one end of the through shaft is used,

the diameter of each through hole of the external lead, the external insulating member, the internal insulating member and the internal lead through which the through shaft of the connection terminal is inserted is formed to be substantially equal to the diameter of the through shaft, and the diameter of the through hole of the outer package body through which the through shaft of the connection terminal is inserted is formed larger than the diameter of the through shaft in advance, and the through shaft of the connection terminal is inserted through the through holes of the outer lead, the outer insulating member, the outer package body, the inner insulating member, and the inner lead, a new collar portion is formed by caulking the other end of the through shaft, and the other end of the through shaft is connected to the outer lead and the inner lead via the plate-like outer lead and the inner lead, and applying caulking pressure to the outer insulating member, the outer package, and the inner insulating member, and pressing the outer insulating member or the inner insulating member into a space between the through hole of the outer package and the through shaft, which are formed in a large size in advance.

12. A method for manufacturing an electricity storage device, the electricity storage device comprising: a battery element housed in an exterior body having at least a metal layer; a plate-shaped inner lead connected to the battery element inside the outer package; a plate-shaped external lead arranged outside the outer package body so as to face the internal lead; a connection terminal electrically connecting the inner lead and the outer lead; an inner insulating member provided between the outer package and the inner lead along an inner surface of the outer package; an outer insulating member provided between the outer package and an outer lead along an outer surface of the outer package so as to face the inner insulating member,

a connection terminal having a through shaft and a flange formed in advance at one end of the through shaft is used,

the diameter of each through hole of the external lead, the external insulating member, the internal insulating member and the internal lead through which the through shaft of the connection terminal is inserted is formed to be substantially equal to the diameter of the through shaft, and the diameter of the through hole of the outer package body through which the through shaft of the connection terminal is inserted is formed larger than the diameter of the through shaft in advance, and the through shaft of the connection terminal is inserted through the through holes of the outer lead, the outer insulating member, the outer package body, the inner insulating member, and the inner lead, a new collar portion is formed by caulking the other end of the through shaft, and the other end of the through shaft is connected to the outer lead and the inner lead via the plate-like outer lead and the inner lead, the outer insulating member, the outer package, and the inner insulating member are pressed into a space between the through hole of the outer package and the through shaft, which are formed in a large size in advance, by applying caulking pressure to the outer insulating member, the outer package, and the inner insulating member.

13. The method for manufacturing an electric storage device according to claim 11 or 12, wherein the outer package is a multilayer outer package having a heat-sealable inner surface layer made of a thermoplastic resin on an inner surface thereof, and after the outer lead, the outer insulating member, the outer package, the inner insulating member, and the inner lead are connected using the connection terminal, the inner insulating member is folded back at an end portion of the inner lead, and the end portion of the inner lead, the end portion of the battery element, and the flange portion of the connection terminal are covered so as to follow a surface of the end portion of the inner lead, the end portion of the battery element, and the flange portion of the connection terminal, and then housed in the outer package.