JP5119615B2 - Secondary battery and assembled battery - Google Patents

Description

  The invention provides a secondary battery in which a power generation element having an electrode plate is accommodated in an exterior member and sealed, and an electrode terminal connected to the electrode plate via a conductive member is led out from the exterior member, and The present invention relates to an assembled battery in which a plurality of secondary batteries are stacked and these are electrically connected.

  In the secondary battery in which the power generation element having the electrode plate is accommodated in the exterior member and sealed, and the electrode terminal connected to the electrode plate via the conductive member is led out from the exterior member, in the event of an abnormality such as overcharge Gas may be generated inside the battery and the internal pressure may increase. In order to eliminate such an increase in internal pressure, a technique has been conventionally known in which a secondary blade is provided with a cutting blade capable of perforating the exterior member when the exterior member expands, and gas is released from the perforation to the outside. (For example, refer to Patent Document 1).

  However, with this technology, even if the internal pressure of the battery can be reduced by releasing the gas, the overcharge state continues and the gas generation itself cannot be suppressed.

JP 2001-222986 A

  An object of this invention is to provide the secondary battery which can stop or relieve abnormalities, such as an overcharge.

To achieve the above object, according to the present invention, a power generating element formed by laminating positive and negative electrode plates, a metal layer, and an insulating layer laminated on one surface side of the metal layer, An exterior member formed in a bag shape with the insulating layer inside, and an electrode terminal connected to the electrode plate via a conductive member, and the power generation element is the exterior member A secondary battery in which the exterior member is sealed along an outer peripheral edge, and the electrode terminal is led out from the exterior member . The secondary battery is provided with an easily meltable portion that is easier to melt than other portions of the insulating layer at a portion of the insulating layer facing the conductive member.

  In the present invention, in the insulating layer of the exterior member, an easily melting portion that is relatively easier to melt than other portions is formed in the portion facing the conductive member that connects the electrode plate and the electrode terminal, and abnormal heat generation of the battery Sometimes this easy melting part is melted first, and the metal layer of the exterior member is exposed to the conductive member. As a result, when an abnormality occurs, the metal layer and the conductive member are conducted, and the energy inside the battery is discharged to the metal layer. Therefore, the secondary battery is short-circuited to stop the abnormality, or the secondary battery is spontaneously discharged. Can alleviate the abnormality.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1 and 2 are a plan view and a side view showing the entire thin battery according to the embodiment of the present invention, FIG. 3 is an enlarged sectional view taken along line III-III of FIG. 1, and FIGS. FIG. 7 is a sectional view taken along line VII-VII in FIG.

  1 and 2 show one thin battery 1 (unit battery), and an assembled battery having a desired voltage and capacity is configured by electrically connecting a plurality of the thin batteries 1.

  The thin battery 1 according to the present embodiment is a stackable flat (thin) lithium ion secondary battery, and as illustrated in FIGS. 1 to 3, the power generation element 10, the exterior member 40, and the electrode terminals 20 and 30. For example, and has a total thickness of 10 mm or less.

  As shown in FIG. 4, the power generation element 10 includes a positive electrode plate 11, a separator 12, a negative electrode plate 13, and an electrolyte (not shown). The positive electrode plate 11 and the negative electrode plate 13 are interposed via the separator 12. Are alternately stacked. Hereinafter, the positive electrode plate 11 is referred to as a positive electrode plate 11, the negative electrode plate 13 is referred to as a negative electrode plate 13, and the positive and negative electrode plates are collectively referred to as an electrode plate.

  The positive electrode plate 11 includes a positive electrode side current collector 11a and positive electrode layers 11b and 11c respectively formed on both main surfaces of the positive electrode side current collector 11a. The positive electrode layer 20 is connected to the positive electrode terminal 20 through the positive electrode side conductive member 25 in which the positive electrode layers 11b and 11c are not formed.

  The positive electrode side current collector 11a is made of an electrochemically stable metal foil such as an aluminum foil, an aluminum alloy foil, or a nickel foil.

Positive electrode layer 11b, 11c can, for example, lithium-nickel composite oxide such as LiNiO _2, lithium-manganese-based composite oxide such as LiMn ₂ O _4, or the like Ya lithium cobalt-based composite oxide such as LiCoO _2, A positive electrode side current collector obtained by mixing a positive electrode active material such as a chalcogen (S, Se, Te) compound, a conductive agent such as carbon black, and a binder such as an aqueous dispersion of polyfluorinated ethylene. It is formed by applying to both main surfaces of 11a, drying and compressing.

  In the present embodiment, the positive electrode layers 11b and 11c are not formed at one end of the positive electrode current collector 11a, and the positive electrode current collector 11a in the portion where the positive electrode layers 11b and 11c are not formed is the positive electrode. The side conductive member 25 is configured. The positive electrode side conductive member 25 is joined to the inner end of the positive electrode terminal 20 by a technique such as ultrasonic welding. In the present invention, the present invention is not particularly limited to this, and the positive electrode side conductive member 25 may be formed of a member different from the positive electrode side current collector 11a.

  The negative electrode plate 13 includes a negative electrode side current collector 13a and negative electrode layers 13b and 13c formed on both main surfaces of the negative electrode side current collector 13a. The positive electrode side current collector 13a includes: The negative electrode layer 30 is connected to the negative electrode terminal 30 through the negative electrode side conductive member 35 on which the negative electrode layers 13b and 13c are not formed.

  The negative electrode side current collector 13a is an electrochemically stable metal foil such as a nickel foil, a copper foil, a stainless steel foil, or an iron foil.

  The negative electrode layers 13b and 13c are formed of, for example, an organic material into the negative electrode active material that occludes and releases lithium ions of the positive electrode active material, such as amorphous carbon, non-graphitizable carbon, graphitizable carbon, or graphite. An aqueous dispersion of styrene butadiene rubber resin powder as a precursor material of the fired body is mixed, dried, and pulverized, so that the carbon material surface carries carbonized styrene butadiene rubber as the main material. Further, a binder such as an acrylic resin emulsion is further mixed, and this mixture is applied to both main surfaces of the negative electrode side current collector 13a, dried and compressed.

  In the present embodiment, the negative electrode layers 13b and 13c are not formed at one end of the negative electrode side current collector 13a, and the negative electrode side current collector 13a in a portion where the negative electrode layers 13b and 13c are not formed is the negative electrode. A side conductive member 35 is formed. The negative electrode side conductive member 35 is joined to the inner end of the negative electrode terminal 30 by a technique such as ultrasonic welding. In the present invention, the present invention is not particularly limited to this, and the negative electrode side conductive member 35 may be formed of a member different from the negative electrode side current collector 13a.

  The separator 12 prevents a short circuit between the positive electrode plate 11 and the negative electrode plate 13 described above, and may have a function of holding an electrolyte. This separator 12 is a microporous film made of polyolefin such as polyethylene (PE) or polypropylene (PP), for example. When an overcurrent flows, the pores of the layer are blocked by the heat generation and the current is cut off. It also has a function to

  The separator in the present invention is not limited to a single-layer film such as polyolefin, but may be a three-layer structure in which a polypropylene film is sandwiched with a polyethylene film, or a laminate of a polyolefin microporous film and an organic nonwoven fabric or the like. it can. Thus, by making a separator into a multilayer, various functions, such as an overcurrent prevention function, an electrolyte holding function, and a separator shape maintenance (stiffness improvement) function, can be provided.

  The power generation element 10 described above is configured by alternately stacking positive plates 11 and negative plates 13 with separators 12 interposed therebetween. All the positive plates 11 are connected to the positive terminal 20 made of metal foil through the positive electrode side conductive member 25, while all the negative plates 13 are also made of the same metal through the negative electrode side conductive member 35. It is connected to the negative electrode terminal 30 made of foil.

  The number of the positive electrode plate 11, the separator 12 and the negative electrode plate 13 constituting the power generation element 10 can be selected and configured as required. For example, one positive plate 11, one separator The power generation element 10 can also be configured with 12 and one negative electrode plate 13.

  The positive electrode terminal 20 and the negative electrode terminal 30 are not particularly limited as long as they are electrochemically stable metal materials. As the positive electrode terminal 20, for example, an aluminum foil or an aluminum alloy foil can be used as in the positive electrode current collector 11 described above. , Copper foil, or nickel foil. Moreover, as the negative electrode terminal 30, the nickel foil, copper foil, stainless steel foil, or iron foil etc. can be mentioned similarly to the above-mentioned negative electrode side collector 13a, for example.

  The power generation element 10 configured as described above is housed and sealed in the exterior member 40. The exterior member 40 includes a sheet-like upper exterior member 41 (upper sheet member) that covers the power generation element 10 from above, and a sheet-like lower exterior member 42 (lower part) that faces the upper exterior member 41 and covers the power generation element 10 from below. Sheet member).

  As shown in FIGS. 2 and 3, the upper exterior member 41 has a cup-shaped outer shape that can accommodate the power generation element 10. As shown in FIG. 5, the upper exterior member 41 is formed by laminating an outer resin layer 41a, an adhesive layer 41b, a metal layer 41c, and an inner resin layer 41d from the outer side to the inner side of the thin battery 1. . The outer resin layer 41a is made of a resin film excellent in electrical insulation, such as a polyamide resin or a polyester resin. The outer resin layer 41a and the metal layer 41c are bonded via an adhesive layer 41b, and the metal layer 41c is made of a metal foil such as an aluminum foil. The inner resin layer 41d is made of a resin film excellent in electrolytic solution resistance and heat fusion property such as polyethylene or polypropylene.

  On the other hand, the lower exterior member 42 has a flat outer shape as shown in FIGS. Similar to the upper exterior member 41, the lower exterior member 42 is formed by laminating an outer resin layer 42a, an adhesive layer 42b, a metal layer 42c, and an inner resin layer 42d from the outside to the inside of the thin battery 1. Yes. The outer resin layer 42a is made of, for example, a resin film excellent in electrical insulation, such as a polyamide resin or a polyester resin. The outer resin layer 42a and the metal layer 42c are bonded via an adhesive layer 42b, and the metal layer 42c is made of a metal foil such as an aluminum foil, for example. The inner resin layer 42d is made of, for example, a resin film excellent in electrolytic solution resistance and heat fusion property such as polyethylene and polypropylene.

In the present embodiment, as shown in FIGS. 3 and 6, an easily melting portion 41 e is formed in a portion of the inner resin layer 41 d of the upper exterior member 41 that faces the positive electrode side conductive member 25. In the inner resin layer 41d, while the other portions other than the easily melting portion 41e has a thickness _{t 0,} easily melted portion 41e has a thickness _{t 1 (t 1 <t 0} ) The easily meltable portion 41e is relatively thinner than other portions of the inner resin layer 41d. Further, although not particularly illustrated, the thickness of the inner resin layer 41d of the upper exterior member 41 facing the negative electrode side conductive member 35 is also relatively smaller than that of the other portion on the negative electrode side. A thin easily melting part 41e is formed.

  The easy melting part 41e is easier to melt than the other part of the inner resin layer 41d, and when the battery is abnormally heated, the easy melting part 41e is melted first, and the metal layer 41c becomes the positive electrode side conductive member 25. To be exposed. For this reason, when the abnormality occurs, the metal layer 41c and the positive electrode side conductive member 25 are electrically connected, and the energy inside the battery is discharged to the metal layer 41c of the upper exterior member 41. Therefore, the thin battery 1 is short-circuited to stop the abnormality. Abnormalities can be alleviated by promoting natural discharge of thin batteries.

  For example, when a charger is connected to the battery and a charging current is supplied from the outside of the battery, the metal layer 41e can bypass the charging current.

  In the present embodiment, the easy melting part 41e is made thinner than the other part of the inner resin layer 41d by making the easy melting part 41e thinner. However, the present invention is not particularly limited to this. For example, other than the easily meltable part 41e of the inner resin layer 41d of the upper exterior member 41 may be made of polypropylene, and the easily meltable part 41e may be made of polyethylene having a melting point lower than that of polypropylene.

  In the present embodiment, as illustrated in FIG. 3, a seal made of, for example, polypropylene is provided between the positive electrode terminal 20 and the exterior member 40 in order to maintain the sealing performance in the battery 1. A member 43 is interposed. Similarly, although not particularly illustrated, a seal member 43 is also interposed between the negative electrode terminal 30 and the exterior member 40.

  In the present embodiment, as shown in FIG. 7, for example, in the corner portion of the exterior member 40, a part of the inner resin layer 41 d of the upper exterior member 41 is peeled off and the metal layer 41 c is exposed, A part of the inner resin layer 42d of the lower exterior member 42 is also peeled off to expose the metal layer 42c, and the exposed metal layers 41c and 42c are in contact with each other and are conductive.

  In this way, by conducting the metal layers 41c and 42c to each other, a current flows through the metal layer 42c of the lower exterior member 42 in addition to the metal layer 41c of the upper exterior member 41 when a battery abnormality occurs. The discharge current of the battery 1 can be increased.

  In the present invention, the upper exterior member 41 and the lower exterior member 42 may be formed of a single laminate material by bending the single resin-metal thin film laminate material to form the exterior member 40. In this case, the metal layer 41c of the upper exterior member 41 and the metal layer 42c of the lower exterior member 42 are connected from the beginning.

The exterior member 40 configured as described above encloses part of the power generation element 10, the positive electrode terminal 20, and the negative electrode terminal 30 described above, and in the space formed by the exterior member 40, lithium perchlorate ( While injecting a liquid electrolyte in which a lithium salt such as LiClO ₄ ), lithium borofluoride (LiBF ₄ ), or lithium hexafluorophosphate (LiPF ₆ ) is used as a solute, the space formed by the exterior member 40 is sucked and decompressed. Then, the exterior member 40 is sealed by heat fusion along the outer peripheral edge by a heat fusion machine such as a heat sealer.

  Examples of the organic liquid solvent include ester solvents such as propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), and methyl ethyl carbonate (MEC). Without being limited thereto, ether solvents such as γ-butylactone (γ-BL) and diethoxyethane (DEE) and other mixed organic liquid solvents can be used as the ester solvent.

  FIG. 8 is a partial cross-sectional view showing an assembled battery according to an embodiment of the present invention.

  As shown in FIG. 8, the assembled battery 100 according to the present embodiment includes two thin batteries 1A and 1B, two elastic members 102a and 102b, and a case 101 that houses them.

  Each of the thin batteries 1A and 1B has the same configuration as the thin battery 1 described above, and is stacked along the thickness direction so that the positive electrode terminal 20 faces substantially the same direction. In these thin batteries 1A and 1B, the positive terminals 20 are joined and electrically connected in parallel.

  An elastic member 102 a that can be elastically deformed is interposed between the upper thin battery 1 </ b> A and the inner upper surface of the case 101. The elastic member 102a presses a portion of the upper exterior member 41 of the thin battery 1A where the easily meltable portion 41e is formed from the outside of the battery. An elastic member 102b that can be elastically deformed is interposed between the thin batteries 1A and 1B. This elastic member 102b also presses the portion of the upper exterior member 41 of the thin battery 1B where the easily meltable portion 41e is formed from the outside of the battery. These elastic members 102a and 102b can be made of, for example, a mechanical spring, a flexible synthetic resin material, an elastomer, or the like.

  Although not particularly illustrated, elastic members 102a and 102b are formed on the negative electrode side between the upper thin battery 1A and the case and between the thin batteries 1A and 1B, respectively. The elastic members 102a and 102b press the portion of the exterior member 41 where the easily meltable portion 41e is formed from the outside of the battery.

  When the easily melting part 41e is melted when a battery abnormality occurs, the exposed metal layer 41c and the positive electrode-side conductive member 25 can be reliably brought into contact with each other by pressing the upper exterior member 41 with the elastic members 102a and 102b. it can.

  The embodiment described above is described for facilitating the understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  In the above-described embodiment, the assembled battery 100 is configured by using the two thin batteries 1A and 1B. However, the number of the thin batteries constituting the assembled battery in the present invention is not particularly limited to this, and the required voltage and capacity are not limited. Depending on the above, the assembled battery may be configured using three or more thin batteries.

  In the above-described embodiment, the assembled battery 100 is configured by connecting the thin batteries 1A and 1B in series. However, the present invention is not particularly limited, and the thin batteries are arranged in parallel according to the required voltage, capacity, and the like. Connection or series / parallel may be mixed and connected.

  Below, the effect of the present invention was confirmed by examples and comparative examples that further embody the present invention. The following examples and comparative examples are for confirming the effects of the thin battery and the assembled battery according to the above-described embodiment.

Example 1
Powder obtained by mixing spinel type lithium manganese oxide with graphite and polyvinylidene fluoride (PVDF) is dispersed in N-methyl-2-pyrrolidone (NMP) to form a slurry, and this slurry is formed on both main surfaces of an aluminum foil having a thickness of 20 μm. After coating and drying, a positive electrode plate was prepared by compression and cutting. In addition, it was set as the positive electrode side electrically-conductive member for connecting a positive electrode plate to a positive electrode terminal, without apply | coating a slurry to a part of aluminum foil.

  Also, a powder obtained by mixing non-graphitizable carbon and polyvinylidene fluoride (PVDF) is dispersed in N-methyl-2-pyrrolidone (NMP) to form a slurry, and this slurry is applied to both main surfaces of a 10 μm thick copper foil. And dried, and then compressed and cut to prepare a negative electrode plate. In addition, it was set as the negative electrode side electrically-conductive member for connecting a negative electrode plate and a negative electrode terminal, without apply | coating a slurry to a part of copper foil.

  The positive electrode plate and the negative electrode plate thus produced were alternately laminated so that a separator was sandwiched between them and the negative electrode plate was positioned on the outermost side to obtain an electrode laminate. A 25 μm microporous polyethylene film was used as a separator. The size of this electrode laminate was 200 mm long × 120 mm wide × 3 mm high.

  Each positive electrode side conductive member extending from the electrode laminate was welded to the positive terminal, and each negative electrode conductive member extending from the laminate was welded to the negative terminal. An aluminum foil having a thickness of 100 μm was used as the positive electrode terminal. Further, a nickel foil having a thickness of 100 μm was used as the negative electrode terminal.

  Next, the electrode laminate connected to the electrode terminal is accommodated between the two exterior members, and in a state where a part of the electrode terminal is led out from the outer peripheral edge, After heat-sealing a total of three sides on the long side and injecting a predetermined amount of electrolyte from the opening, the remaining one side is heat-sealed while the space formed by the exterior member is decompressed. The battery sample of Example 1 was produced.

  The upper exterior member and the lower exterior member are composed of a nylon layer having an outer resin layer thickness of 15 μm, an aluminum alloy layer having a metal layer thickness of 40 μm, and a polypropylene layer having an inner resin layer thickness of 45 μm. A layered resin-metal thin film laminate was used.

  Moreover, in Example 1, the thickness of the part which each opposed to the positive electrode side electrically-conductive member and the negative electrode side electrically-conductive member in an inner side resin layer was made thin (it set to 15 micrometers in this Example), and the easily meltable part was formed.

As the electrolytic solution, a mixed solvent of propylene carbonate (PC), ethylene carbonate (EC) and diethyl carbonate (DEC) in which lithium hexafluorophosphate (LiPF ₆ ) was dissolved as a supporting electrolyte was used.

  Eight battery samples as described above were stacked in the thickness direction, and the eight battery samples were accommodated in a case to form the assembled battery of Example 1. At this time, the adjacent battery samples were stacked in such a direction that the electrode terminals with different polarities face each other, and eight battery samples were connected in series.

  Table 1 shows the sample preparation conditions in Example 1.

この実施例１では５個の組電池サンプルについて以下のような過充電試験と釘刺し試験を行い、電池の異常発生の評価を行った。

In Example 1, the following overcharge test and nail penetration test were performed on five assembled battery samples to evaluate the occurrence of battery abnormality.

  In the overcharge test, the state of charge (SOC) of 100% is maintained at a constant current, and charging is performed with the target of SOC 250%. If the temperature does not reach 200 ° C., it is evaluated as “◎”. If even one sample does not reach the battery temperature of 200 ° C., it is evaluated as “◯”. When it reached ° C., it was evaluated as “×”.

  In the nail penetration test, an iron nail was penetrated in the thickness direction of the assembled battery, and after that, when any of the samples did not reach the battery temperature of 200 ° C., the evaluation was “◎”. When the battery temperature did not reach 200 ° C., it was evaluated as “◯”, and when the temperature of all the samples reached 200 ° C., it was evaluated as “x”.

  Table 2 shows the results of the overcharge test and the nail penetration test of Example 1.

実施例２
実施例２では、弾性部材が、各薄型電池の上部外装部材において易溶融部が形成されている部分を押圧するように、各電池サンプルの間、及び、ケース内側上面と電池サンプルとの間に弾性部材をそれぞれ配置した。それ以外は、実施例１と同様の条件で組電池サンプルを作製した。実施例２におけるサンプルの作製条件を上記の表１に示す。

Example 2
In Example 2, the elastic member presses the portion where the easily meltable portion is formed in the upper exterior member of each thin battery, and between the battery samples and between the case inner upper surface and the battery sample. Each elastic member was arranged. Otherwise, an assembled battery sample was produced under the same conditions as in Example 1. The sample production conditions in Example 2 are shown in Table 1 above.

  An overcharge test and a nail penetration test were performed on the five samples of Example 2 under the same conditions as in Example 1. The results of the overcharge test and the nail penetration test of Example 2 are shown in Table 2 above.

Example 3
In Example 3, in the inner resin layer of each thin battery constituting the assembled battery, the thickness of the inner resin layer is constant, and the portions facing the positive electrode side conductive member and the negative electrode side conductive member are made of polypropylene (melting point). An easily meltable part was formed from polyethylene (melting point: about 110 ° C.) having a melting point lower than that of about 150 ° C.). Otherwise, an assembled battery sample was produced under the same conditions as in Example 1. The production conditions of the sample in Example 3 are shown in Table 1 above.

  An overcharge test and a nail penetration test were performed on the five samples of Example 3 under the same conditions as in Example 1. The results of the overcharge test and the nail penetration test of Example 3 are shown in Table 2 above.

Example 4
In Example 4, the elastic member is elastic between each battery sample and between the case inner upper surface and the battery sample so as to press the portion where the easily meltable portion is formed in the upper exterior member of each thin battery. Each member was arranged. Otherwise, an assembled battery sample was produced under the same conditions as in Example 3. The sample production conditions in Example 4 are shown in Table 1 above.

  An overcharge test and a nail penetration test were performed on the five samples of Example 4 under the same conditions as in Example 1. The results of the overcharge test and the nail penetration test of Example 4 are shown in Table 2 above.

Comparative Example 1
In Comparative Example 1, an assembled battery sample was produced under the same conditions as in Example 1 and Example 3, except that the inner resin layer was not provided with an easily meltable portion. The sample production conditions in Comparative Example 1 are shown in Table 1 above.

  An overcharge test and a nail penetration test were performed on the five samples of Comparative Example 1 under the same conditions as in Example 1. The results of the overcharge test and the nail penetration test of Comparative Example 1 are shown in Table 2 above.

Comparative Example 2
In Comparative Example 2, an assembled battery sample was produced under the same conditions as in Example 2 and Example 4 except that the inner resin layer was not provided with an easily meltable portion. The sample production conditions in Comparative Example 2 are shown in Table 1 above.

  An overcharge test and a nail penetration test were performed on the five samples of Comparative Example 2 under the same conditions as in Example 1. The results of the overcharge test and the nail penetration test of Comparative Example 2 are shown in Table 2 above.

Discussion As shown in Table 2, the assembled battery samples of Examples 1 to 4 gave good results in the nail penetration test. This is presumably because the easily melted portion formed on the upper exterior member of the thin battery melted and the exposed metal layer contacted the conductive member.

  In addition, as shown in the same table, the assembled battery samples of Examples 3 and 4 gave good results in the overcharge test. This is presumably because the elastic member presses the portion where the easily meltable portion is formed in the upper exterior member of the thin battery, and the exposed metal layer is appropriately in contact with the conductive member.

  In the above embodiment, the easily meltable part is formed by either reducing the thickness of a part of the inner resin layer or by using a resin having a low melting point. It is not limited to this, For example, it can change suitably, for example, forming the resin layer thinly and forming with low melting point resin.

FIG. 1 is a plan view showing the overall configuration of a thin battery according to an embodiment of the present invention. FIG. 2 is a side view showing the overall configuration of the thin battery according to the embodiment of the present invention. FIG. 3 is an enlarged cross-sectional view taken along line III-III in FIG. FIG. 4 is an enlarged cross-sectional view of a portion IV in FIG. FIG. 5 is an enlarged cross-sectional view of a portion V in FIG. 6 is an enlarged cross-sectional view of a portion VI in FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. FIG. 8 is a partial cross-sectional view showing the assembled battery according to the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Thin battery 10 ... Electric power generation element 11 ... Positive electrode plate 11a ... Positive electrode side collector 11b, 11c ... Positive electrode layer 12 ... Separator 13 ... Negative electrode plate 13a ... Negative electrode side collector 13b, 13c ... Negative electrode layer 20 ... Positive electrode terminal 25 ... positive electrode side conductive member 30 ... negative electrode terminal 35 ... negative electrode side conductive member 40 ... exterior member 41 ... upper exterior member 41a ... outer resin layer 41b ... adhesive layer 41c ... metal layer 41d ... inner resin layer 41e ... easy melting part 42 ... lower part Exterior member 42a ... Outer resin layer 42b ... Adhesive layer 42c ... Metal layer 42d ... Inner resin layer 43 ... Seal member 100 ... Battery pack 101 ... Case 102a, 102b ... Elastic member

Claims (7)

A power generation element formed by laminating positive and negative electrode plates;
A sheet member having at least a metal layer and an insulating layer laminated on one surface side of the metal layer, an exterior member formed in a bag shape with the insulating layer inside, and
An electrode terminal connected to the electrode plate via a conductive member,
The power generation element is housed in a space formed by the exterior member, the exterior member is sealed along an outer peripheral edge, and the electrode terminal is a secondary battery led out from the exterior member,
The conductive member is located in the space;
The secondary battery in which the easily meltable part which melt | dissolves more easily than the other part of the said insulating layer is formed in the part facing the said electrically-conductive member in the said insulating layer.   The secondary battery according to claim 1, wherein the easily meltable portion of the insulating layer is relatively thinner than other portions of the insulating layer.   The secondary battery according to claim 1, wherein the easily meltable portion of the insulating layer is made of a material having a relatively lower melting point than a material constituting the other part of the insulating layer. The exterior member is composed of an upper sheet member that covers the power generation element from above, and a lower sheet member that covers the power generation element from below,
The secondary battery according to claim 1, wherein the metal layer included in the upper sheet member and the metal layer included in the lower sheet member are electrically connected.   The secondary battery according to any one of claims 1 to 4, further comprising pressing means for pressing a portion of the insulating layer where the easily meltable portion is formed from the outside of the exterior member. A battery pack comprising a plurality of the secondary batteries according to claim 5 stacked together, the electrode terminals of the stacked secondary batteries connected to each other, and the plurality of secondary batteries electrically connected.
The pressing means is a set that is sandwiched between a plurality of the secondary batteries to press a portion where the easily meltable portion is formed in the insulating layer of each secondary battery from the outside of the exterior member. battery.   The assembled battery according to claim 6, wherein the pressing means includes an elastic member that can be elastically deformed.

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