JP4710276B2 - Secondary battery exterior member and secondary battery - Google Patents

Description

  The present invention relates to a secondary battery exterior member for housing and sealing a power generation element of a secondary battery, and a secondary battery using the same.

  As a secondary battery exterior member for containing and sealing a power generation element of a secondary battery, a three-layer structure composed of an inner resin layer, a metal layer, and an outer resin layer is conventionally known ( For example, see Patent Document 1).

In a secondary battery using such a secondary battery exterior member, in order to prevent a potential from being generated in a metal layer located in the middle of the exterior member or an internal short circuit of the battery via the metal layer. It is necessary to ensure electrical insulation that can sufficiently withstand the load (vibration, temperature, humidity, etc.) applied to the inner resin layer of the exterior member in the usage environment. In particular, for example, in the field of electric vehicles, when two or more unit batteries are connected in series and used as an assembled battery, the assembled battery becomes a high voltage, and this problem becomes significant.
JP 2001-307690 A

The present invention provides a secondary battery exterior member capable of preventing potential generation of a metal layer and internal short circuit of the battery via the metal layer under a wide temperature environment, and a secondary battery using the same. With the goal.
In order to achieve the above object, according to the present invention, there is provided a secondary battery exterior member for containing and sealing a power generation element of a secondary battery, wherein the secondary battery exterior member comprises the second battery A first-inner resin layer comprising a resin-metal thin film laminate material that is directly laminated in the order of a first inner resin layer, a second inner resin layer, and a metal layer from the inner side to the outer side of the secondary battery. , the consist second lifting two polypropylenes with higher melting point inner resin layer, said second inner resin layer is formed of a polyethylene material having a first glass transition temperature of less than the inner resin layer exterior member for a secondary battery have is provided.

In order to achieve the above object, according to the present invention, 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 extends from an outer peripheral edge of the exterior member. The derived secondary battery, wherein the exterior member is a resin in which the first inner resin layer, the second inner resin layer, and the metal layer are directly laminated in this order from the inner side to the outer side of the secondary battery. - has a metal thin film laminate, said first inner resin layer is made higher than the second inner resin layer melting point from lifting one polypropylene material, said second inner resin layer, said first A secondary battery composed of a polyethylene material having a glass transition temperature lower than that of the inner resin layer is provided.

  In the present invention, the exterior member used for the secondary battery includes a first inner resin layer having a higher melting point than the second inner resin layer, and a second glass transition temperature lower than that of the first inner resin layer. An inner resin layer, and the first and second inner resin layers are laminated inside the metal layer.

  In a low temperature environment, crystallization of the inner resin layer proceeds to cause a decrease in strength, and vibration or stress is applied to the secondary battery, and cracks may occur in the inner resin layer. On the other hand, in the present invention, even if a crack occurs in the first inner resin layer, the second inner resin layer has a lower glass transition temperature than that of the first inner resin layer. Since the crystallinity of the layer becomes low, the occurrence of cracks in the second inner resin layer can be suppressed. For this reason, it is prevented that the metal layer of the exterior member is exposed through a crack to contact with the electrolyte solution or the electrode plate inside the secondary battery, and the generation of the potential of the metal layer or the battery through the metal layer is prevented. An internal short circuit can be prevented.

  Further, in a high temperature environment, the distance (thickness) necessary for electrical insulation may not be locally secured due to creep of the inner resin layer or the like. On the other hand, in the present invention, even if a creep phenomenon occurs in the second inner resin layer, the first inner resin layer has a higher melting point than the second inner resin layer, so that the electrolysis inside the secondary battery is performed. The distance required for insulation between the liquid, electrode plate, etc. and the metal layer of the exterior member is secured by the first inner resin layer, and it is possible to prevent potential generation of the metal layer and internal short circuit of the battery via the metal layer. It becomes.

  Furthermore, even if the battery temperature rises to near the melting point of the second inner resin layer due to abnormal overheating or the like, in the present invention, the first inner resin layer having a higher melting point than the second inner resin layer does not melt. Therefore, it is possible to prevent the metal layer of the exterior member from being exposed to the electrolyte solution or electrode plate inside the secondary battery, and to prevent potential generation of the metal layer and internal short circuit of the battery via the metal layer. It becomes.

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

  FIG. 1 is an upper plan view showing an entire secondary battery according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1, and FIG. 3 is a secondary battery according to an embodiment of the present invention. It is sectional drawing of this exterior member.

  1 and 2 show one secondary battery 10 (unit battery), and an assembled battery having a desired voltage and capacity is configured by combining a plurality of the secondary batteries 10.

  A secondary battery 10 according to the present embodiment is a lithium-based flat-type laminated thin secondary battery, and includes three positive plates 101 and five separators 102 as shown in FIGS. 1 and 2. And three negative plates 103, a positive electrode terminal 104, a negative electrode terminal 105, an upper exterior member 106, a lower exterior member 107, and an electrolyte (not shown). Among these, the positive electrode plate 101, the separator 102, the negative electrode plate 103, and the electrolyte are particularly referred to as a power generation element 108.

  The positive electrode plate 101 constituting the power generation element 108 includes a positive electrode side current collector 101a extending to the positive electrode terminal 104, and positive electrode layers 101b and 101c formed on both main surfaces of a part of the current collector 101a, have.

  The positive electrode side current collector 101a of the positive electrode plate 101 is an electrochemically stable metal foil such as an aluminum foil, an aluminum alloy foil, a copper foil, or a nickel foil.

The positive electrode layers 101b and 101c of the positive electrode plate 101 are made of, for example, lithium composite oxide such as lithium nickelate (LiNiO ₂ ), lithium manganate (LiMnO ₂ ), or lithium cobaltate (LiCoO ₂ ), or chalcogen. (S, Se, Te) A positive electrode active material such as a compound, a conductive agent such as carbon black, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), an ethylene-propylene-diene copolymer (EPDM) A mixture of a binder such as an aqueous dispersion is applied to both main surfaces of a part of the positive electrode side current collector 101a, and is dried and rolled.

  The negative electrode plate 103 constituting the power generation element 108 includes a negative electrode side current collector 103a extending to the negative electrode terminal 105, and negative electrode layers 103b and 103c respectively formed on both main surfaces of a part of the current collector 103a. have.

  The negative electrode side current collector 103a of the negative electrode plate 103 is an electrochemically stable metal foil such as nickel foil, copper foil, stainless steel foil, or iron foil.

  Further, the negative electrode layers 103b and 103c of the negative electrode plate 103 occlude and release 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 an organic fired body is mixed with the negative electrode active material, and dried and pulverized to support carbonized styrene butadiene rubber on the carbon particle surfaces. It is formed by mixing a binder, such as an acrylic resin emulsion, and applying this mixture to both main surfaces of part of the negative electrode side current collector 103a, followed by drying and rolling. Yes.

  The separator 102 of the power generation element 108 prevents a short circuit between the positive electrode plate 101 and the negative electrode plate 103 described above, and may have a function of holding an electrolyte. This separator 102 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 102 of the present invention is not limited to a single-layer film such as polyolefin, but 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 can also be used. . Thus, by making the separator 102 into multiple layers, various functions such as an overcurrent prevention function, an electrolyte holding function, and a separator shape maintenance (rigidity improvement) function can be provided.

  In the power generation element 108 described above, the positive electrode plates 101 and the negative electrode plates 103 are alternately stacked via the separators 102. The three positive plates 101 are respectively connected to the positive terminal 104 made of metal foil via the positive current collector 101a, while the three negative plates 103 are connected to the negative current collector 103a. In the same manner, each is connected to a negative electrode terminal 105 made of metal foil.

  In addition, the positive electrode plate 101, the separator 102, and the negative electrode plate 103 of the power generation element 108 are not limited to the above number in the present invention. For example, one positive electrode plate 101, three separators 102, and 1 The power generation element 108 can also be configured with a single negative plate 103, and can be configured by selecting the number of positive plates, separators, and negative plates as required.

  The positive electrode terminal 104 and the negative electrode terminal 105 are not particularly limited as long as they are electrochemically stable metal materials. Examples of the positive electrode terminal 104 include, for example, an aluminum foil and an aluminum alloy foil, similar to the positive electrode current collector 101a described above. , Copper foil, or nickel foil. Moreover, as the negative electrode terminal 105, nickel foil, copper foil, stainless steel foil, iron foil, etc. can be mentioned similarly to the above-mentioned negative electrode side collector 103a, for example. In the present embodiment, the metal foils constituting the current collectors 101 a and 103 a of the electrode plates 101 and 103 are extended to the electrode terminals 104 and 105, so that the electrode plates 101 and 103 are directly connected to the electrode terminals 104 and 105. Although connected, the current collectors 101a and 103a of the electrode plates 101 and 103 and the electrode terminals 104 and 105 are connected by a material or component different from the metal foil constituting the current collectors 101a and 103a. Also good.

  The power generation element 108 is accommodated and sealed in the upper exterior member 106 and the lower exterior member 107 (exterior member). As shown in FIG. 3, the upper exterior member 106 in the present embodiment includes a first inner resin layer 106 a, a second inner resin layer 106 b, a metal layer 106 c, and a metal layer 106 c from the inner side to the outer side of the secondary battery 10. The outer resin layer 106d has a four-layer resin-metal thin film laminate material (laminate film). Similarly, the lower exterior member 107 has a first inner resin layer 107a, a second inner resin layer 107b, a metal layer 107c, and an outer side from the inner side to the outer side of the secondary battery 10, as shown in FIG. The resin layer 107d is composed of a four-layer resin-metal thin film laminate material (laminate film).

  The first inner resin layers 106a and 107a of the exterior members 106 and 107 are made of a thermoplastic resin material such as polypropylene (PP) having a higher melting point (Tm) than the second inner resin layers 106b and 107b. It is a film.

  In this manner, the first inner resin layers 106a and 107a having a higher melting point than the second inner resin layer are laminated on the inner sides of the second inner resin layers 106b and 107b, so that the second inner resin layers 106a and 107b are stacked in a high temperature environment. Even when the inner resin layers 106b and 107b of the first resin layer 106b cannot secure the distance necessary for electrical insulation due to creep or the like, the first inner resin layers 106a and 107a can generate the power generation element 108 inside the secondary battery 10. And a distance necessary for insulation between the exterior members 106 and 107 and the metal layers 106c and 107c.

  Even when the battery temperature rises to near the melting point of the second inner resin layers 106b and 107b due to abnormal overheating or the like, the high melting point first inner resin layers 106a and 107a do not melt, so the metal layer 106c 107 c are prevented from being exposed to the power generation element 108 of the secondary battery 10.

  Furthermore, since heat absorption occurs at the melting points of the second inner resin layers 106b and 107b, the self-heating of the secondary battery 10 can be suppressed, and the reliability when the secondary battery 10 is abnormal can be greatly improved. It becomes.

  The second inner resin layers 106b and 107b of the exterior members 106 and 107 are made of a thermoplastic resin material such as polyethylene (PE) having a glass transition temperature (Tg) lower than that of the first inner resin layers 106a and 107a. Resin film.

  Thus, by laminating the second inner resin layers 106b and 107b having a glass transition temperature lower than that of the first inner resin layers 106a and 107a on the outside of the first inner resin layers 106a and 107a, a low-temperature environment is obtained. Even when crystallization of the first inner resin layers 106a and 107a progresses and cracks occur, the crystallinity of the second inner resin layers 106b and 107b is low. In the second inner resin layers 106b and 107b, generation of cracks is suppressed. For this reason, it is prevented that the metal layers 106c and 107c of the exterior members 106 and 107 are exposed through the cracks and come into contact with the electrolytic solution or the electrode plate in the secondary battery 10.

  Incidentally, when the second inner resin layers 106b and 107b are laminated inside the first inner resin layers 106a and 107a, the second inner resin not having a high melting point due to heat generated from the inside of the secondary battery 10. Since the layers 106b and 107b are melted, the heat-sealed portions of the exterior members 106 and 107 are peeled off, and the sealing performance may not be ensured. On the other hand, in this embodiment, the sealing properties of the exterior members 106 and 107 can be ensured by laminating the first inner resin layers 106a and 107a on the inner side of the second inner resin layers 106b and 107b. In particular, this effect is remarkable in a field where high voltage and large capacity are required, such as an electric vehicle.

  The first inner resin layers 106a and 107a have a thickness of 20 μm or more, and the second inner resin layers 106b and 107b have a thickness of 15 μm or more.

  Since the first inner resin layers 106a and 107a and the second inner resin layers 106b and 107b have the thicknesses as described above, the first inner resin layers 106a and 107a or the second inner resin layers 106b, Even when dielectric breakdown occurs in one of the layers 107b, the other layer can ensure electrical insulation of the inner resin layer when a high voltage of about 500V is applied.

  The metal layers 106c and 107c of the exterior members 106 and 107 are made of a metal foil such as aluminum. By providing the metal layers 106c and 107c in addition to the resin layer, the strength of the exterior members 106 and 107 themselves can be improved.

  The outer resin layers 106d and 107d of the exterior members 106 and 107 are resin films made of a synthetic resin material having excellent electrical insulation, such as a polyamide resin or a polyester resin. In both the upper exterior member 106 and the lower exterior member 107, a resin layer made of, for example, polyethylene terephthalate (PET) may be laminated on the outer side of the outer resin layers 106d and 107d.

The positive terminal 104 is led out from one end of the exterior members 106 and 107. In this embodiment, in order to maintain the sealing performance in the secondary battery 10, the positive terminal 105 and the exterior members 106 and 107 The sheet film 109 is interposed at the portion where the contact is made. Similarly, the negative electrode terminal 105 is led out from the other end of the exterior members 106 and 107, but the sheet film 109 is interposed at a portion where the negative electrode terminal 105 and the exterior members 106 and 107 are in contact with each other. The sheet film 109 has a thickness of about 50 to 100 μm. Examples of the material constituting the sheet film 109 include polyethylene, polyethylene, modified polyethylene, polypropylene, modified polypropylene, or a synthetic resin material excellent in electrolytic solution resistance and heat fusion properties such as ionomer. From the viewpoint of heat-fusibility, it is preferable that the first inner resin layers 106a and 107a of the exterior members 106 and 107 are made of the same material as the exterior members 106 and 107. A part of the terminal 104 and a part of the negative electrode terminal 105 are wrapped, and in the space formed by the exterior members 106 and 107, an organic liquid solvent is lithium perchlorate (LiClO ₄ ), lithium borofluoride (LiBF ₄ ), six A liquid electrolyte in which a lithium salt such as lithium fluorophosphate (LiPF ₆ ) is used as a solute While injecting, the space formed by the exterior members 106 and 107 is sucked into a vacuum state, and then the outer peripheral edges of the exterior members 106 and 107 are heat-sealed by hot press and sealed.

  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 limitation, an ether solvent such as γ-butylactone (γ-BL), and dietoshikiethane (DEE), or a mixed organic liquid solvent may be used as the ester solvent.

  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. For example, in the above-described embodiment, as shown in FIG. 1, the positive electrode terminal 104 and the negative electrode terminal 105 are respectively led out from the opposing short sides of the exterior members 106 and 107 of the secondary battery 10. For example, the positive electrode terminal 104 and the negative electrode terminal 105 may be led out in the same direction from the same short side of the exterior members 106 and 107.

  Hereinafter, the effects of the present invention were 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 secondary batteries used in the above-described embodiments.

Example 1
A powder obtained by mixing spinel type lithium manganese oxide (positive electrode active material) with graphite (conductive agent) and polyvinylidene fluoride (PVDF) is dispersed in N-methyl-2-pyrrolidone (NMP) to form a slurry, and the slurry is made of aluminum. After substantially uniformly applying to both main surfaces of a part of the foil (current collector on the positive electrode side), a positive electrode plate was produced by rolling to a predetermined density by a roll press.

  A powder obtained by mixing non-graphitizable carbon (negative electrode active material) with graphite (conductive agent) and polyvinylidene fluoride (PVDF) is dispersed in N-methyl-2-pyrrolidone (NMP) to form a slurry. A negative electrode plate was produced by applying substantially uniformly to both main surfaces of a part of the negative electrode side current collector) and then rolling to a predetermined density by a roll press.

  The positive electrode plate and the negative electrode plate thus produced were alternately laminated so that the separator was sandwiched between them and the negative electrode plate was positioned on the uppermost layer and the lowermost layer to form an electrode laminate. The number of stacked electrode plates was set so as to ensure a predetermined battery capacity.

  Each positive current collector extending from the electrode laminate was welded to an aluminum positive terminal, and each negative current collector extending from the laminate was welded to a nickel negative terminal.

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

  The exterior member is composed of a 25 μm thick polypropylene layer as the first inner resin layer, a 20 μm thick polyethylene layer as the second inner resin layer, an aluminum alloy layer as the metal layer, and a nylon layer as the outer resin layer. 4 layer resin-metal thin film laminate material.

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

  Regarding the secondary battery in Example 1, the presence or absence of potential generation of the metal layer under a low temperature environment, the presence or absence of potential generation of the metal layer under a high temperature environment, and the presence or absence of self-heating during abnormal overheating were evaluated.

  The evaluation of the presence or absence of potential generation of the metal layer in a low temperature environment is performed by storing 20 battery samples in an environment at a temperature of −40 ° C. for 1000 hours, and then the potential difference between the metal layer of the exterior member and the positive electrode terminal / negative electrode terminal. When no potential is generated in the metal layer for any battery sample, it is evaluated as “good”, and when no potential is generated in the metal layer even for one sample, it is evaluated as “impossible”. did.

  In this test under a low temperature environment in Example 1, no potential was generated in the metal layer in one of the 20 battery samples. The test results are shown in Table 1. Each numerical value in the column of “low temperature environmental potential test” in Table 1 indicates the number of samples in which a potential is generated in the metal layer among the 20 samples in the test under the low temperature environment.

  The evaluation of the presence or absence of potential generation of the metal layer in a high temperature environment was conducted by storing 20 battery samples in an environment of 80 ° C. for 48 hours, and then measuring the potential difference between the metal layer of the exterior member and the positive electrode terminal / negative electrode terminal. Measured and evaluated as “good” when no potential was generated in the metal layer for any of the battery samples, and “impossible” when potential was generated in the metal layer even for one sample. .

  In this test under a high temperature environment in Example 1, no potential was generated in the metal layer in one of the 20 battery samples. The test results are shown in Table 1. Each numerical value in the column of “High Temperature Environmental Potential Test” in Table 1 indicates the number of samples in which a potential is generated in the metal layer among the 20 samples in the test under the high temperature environment.

  Self-heating during abnormal overheating is evaluated by repeating the charge / discharge cycle until the battery capacity is reduced to 90% of the initial value in an environment at a temperature of 45 ° C., and then putting the battery sample in a thermostatic chamber. The temperature was raised to 160 ° C. at a rate of temperature increase of 5 ° C./min and held at 160 ° C. for 60 minutes, then the temperature of the secondary battery was measured, and no self-heating occurred in any of the battery samples. In some cases, it was evaluated as “good”, and when even one sample had self-heating, it was evaluated as “impossible”.

In this test at the time of abnormal overheating in Example 1, one of the 20 battery samples did not cause self-heating. The test results are shown in Table 1. Each numerical value in the column of “Abnormal Overheating Test” in Table 1 indicates the number of samples that generated self-heating among 20 samples in the test during abnormal overheating.

Comparative Example 1
The secondary battery of Comparative Example 1 is a resin-metal having a three-layer structure in which an exterior member is composed of a polyethylene layer having a thickness of 45 μm as an inner resin layer, an aluminum alloy layer as a metal layer, and a nylon layer as an outer resin layer. A structure similar to that of Example 1 was prepared except that the thin film laminate material was used.

  About the battery sample of this comparative example 1, on the same conditions as Example 1, evaluation of the presence or absence of electric potential generation of the metal layer in a low temperature environment, the presence or absence of electric potential generation of the metal layer in a high temperature environment, and abnormal overheating The presence or absence of self-heating at the time was evaluated.

  As a result, as shown in Table 1, in the test under the low temperature environment, no potential was generated in the metal layer in one of the 20 battery samples. On the other hand, in the test under a high temperature environment, electric potential was generated in the metal layer of 18 samples out of 20 battery samples, and it was evaluated as “impossible”. Further, in the test at the time of abnormal overheating, 5 samples out of 20 battery samples were self-heated and evaluated as “impossible”.

Comparative Example 2
The secondary battery of Comparative Example 2 is a resin-metal having a three-layer structure in which an exterior member is composed of a polypropylene layer having a thickness of 45 μm as an inner resin layer, an aluminum alloy layer as a metal layer, and a nylon layer as an outer resin layer. A structure similar to that of Example 1 was prepared except that the thin film laminate material was used.

  For the battery sample of Comparative Example 2, under the same conditions as in Example 1, evaluation of the presence or absence of potential generation of the metal layer under a low temperature environment, evaluation of the presence or absence of potential generation of the metal layer under a high temperature environment, and The presence or absence of self-heating during abnormal overheating was evaluated.

  As a result, as shown in Table 1, in the test under the low temperature environment, potentials were generated in the metal layers of all the 20 battery samples, and the evaluation was “impossible”. On the other hand, in the test under a high temperature environment, no potential was generated in the metal layer in one of the 20 battery samples. Further, even in the test at the time of abnormal overheating, one of the 20 battery samples did not generate self-heating.

Consideration From the test results under a low temperature environment, it can be seen that the use of polyethylene (PE) having a low glass transition temperature for the inner resin layer of the exterior member prevents the potential generation of the metal layer under the low temperature environment.

  Moreover, it can be seen from the test results in a high temperature environment that the use of polypropylene (PP) having a high melting point for the inner resin layer of the exterior member prevents potential generation of the metal layer in the high temperature environment.

  Furthermore, it can be seen from the test results during abnormal overheating that self-heating of the secondary battery is suppressed by using polypropylene (PP) having a high melting point for the inner resin layer of the exterior member.

FIG. 1 is a top plan view showing an entire secondary battery according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. FIG. 3 is a cross-sectional view of the exterior member of the secondary battery according to the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Secondary battery 101 ... Positive electrode plate 101a ... Positive electrode side collector 101b, 101c ... Positive electrode layer 102 ... Separator 103 ... Negative electrode plate 103a ... Negative electrode side collector 103b, 103c ... Negative electrode layer 104 ... Positive electrode terminal 105 ... Negative electrode terminal DESCRIPTION OF SYMBOLS 106 ... Upper exterior member 106a ... 1st inner side resin layer 106b ... 2nd inner side resin layer 106c ... Metal layer 106d ... Outer side resin layer 107 ... Lower exterior member 107a ... 1st inner side resin layer 107b ... 2nd inner side resin Layer 107c ... Metal layer 107d ... Outside resin layer 108 ... Power generation element 109 ... Sheet film

Claims (3)

A secondary battery exterior member for containing and sealing a power generation element of a secondary battery,
The secondary battery exterior member is a resin-metal thin film laminate in which a first inner resin layer, a second inner resin layer, and a metal layer are directly laminated in this order from the inner side to the outer side of the secondary battery. Have
It said first inner resin layer is composed of the second melting point higher than the inner resin layer from lifting one polypropylene material,
The second inner resin layer is a secondary battery exterior member made of a polyethylene material having a glass transition temperature lower than that of the first inner resin layer. The first inner resin layer has a thickness of 20 μm or more,
It said second inner resin layer, according to claim 1 Symbol placement of the rechargeable battery exterior member having the above 15μm thickness. The exterior member according to claim 1 or 2, is accommodated power generating element having an electrode plate are sealed, rechargeable battery electrode terminal connected to the electrode plate is derived from an outer peripheral edge of the outer member.

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