JP2000277160A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery whose impact resistance is greatly enhanced, followed by only a slight decrease in energy density, when metallic foil laminated with a resin film is used for a battery case. SOLUTION: In this nonaqueous electrolyte secondary battery with a bag- shaped single battery case housing a generating element having a positive electrode plate, a separator and a negative electrode plate, the bag-shaped single battery case has a generating element compartment 1, a case welding part 2, and a gap part 3 therebetween. The widest portion of the case welding part 2 making contact with the gap part 3 is wider than the width of the battery case at a portion including the boundary between the gap part 3 and the generating element compartment 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte secondary battery in which a power generating element is housed in a bag-shaped unit cell case.

[0002]

2. Description of the Related Art In recent years, electronic devices such as a portable radio telephone, a portable personal computer, and a portable video camera have been developed, and various electronic devices have been reduced in size to be portable. Along with this, a battery having a high energy density and a light weight is also adopted as a built-in battery. A typical battery that satisfies such a requirement is an active material such as lithium metal or lithium alloy, or a host material containing lithium ions (here, a host material refers to a material that can occlude and release lithium ions). Lithium intercalation compound occluded in a certain carbon is used as a negative electrode material, and LiC
This is a non-aqueous electrolyte secondary battery using an aprotic organic solvent in which a lithium salt such as l04 and LiPF6 is dissolved as an electrolyte.

This non-aqueous electrolyte secondary battery has a negative electrode plate in which the above-mentioned negative electrode material is held on a negative electrode current collector as a support, and a reversible electrochemical reaction with lithium ions such as a lithium-cobalt composite oxide. The positive electrode plate, which holds the positive electrode active material that reacts on the positive electrode current collector that is the support, from the separator that holds the electrolytic solution and intervenes between the negative electrode plate and the positive electrode plate to prevent a short circuit between the two electrodes Has become.

[0004] Each of the positive electrode plate and the negative electrode plate is formed into a thin sheet or foil shape, and is a power generating element formed by sequentially laminating or spirally winding through a separator. Then, the power generating element is housed in a battery container made of a metal can made of stainless steel, nickel-plated iron, aluminum, or the like. After the electrolyte is injected, the battery is assembled and sealed with a lid plate.

However, when a metal can battery container is used,
Although it is highly airtight and has excellent mechanical strength,
There are great restrictions on battery weight, battery container material and design.

In order to solve the problem, there has been proposed a method using a unit cell case made by laminating a metal foil with a resin film on the material of the unit cell case. By this method,
There is no leakage of electrolyte or intrusion of moisture or the like from the outside of the battery, and the battery can be reduced in weight.

[0007] The shape of the power generating element is a wound type,
In particular, when the cross section is non-circular or oval, the electrode surface area can be increased and the manufacturing process can be simplified.

When such a non-aqueous electrolyte secondary battery is used in electronic equipment, a predetermined voltage is obtained as a unit cell or a plurality of cells connected in series. The single or plural batteries are housed in a housing made of resin or metal and resin together with the charge / discharge control circuit, and sealed so that the contents cannot be taken out, and used as a battery pack.

[0009]

However, a case using a metal foil laminated with a resin film has a lower mechanical strength than a conventional metal can case, and therefore, a case such as a drop or a collision may cause the case to fail. There has been a problem that the corner of the battery is damaged, causing an internal short circuit, and the battery is likely to be defective. In addition, when an internal short circuit occurs due to such an impact on a charged battery, the temperature of the battery rises, which may cause smoke or ignition, which has a problem of high danger.

[0010]

SUMMARY OF THE INVENTION The non-aqueous electrolyte secondary battery according to the present invention has been made in view of the above problems, and comprises a power generating element having a positive electrode plate, an isolator, and a negative electrode plate in a bag-shaped unit cell. In the non-aqueous electrolyte secondary battery housed in the case, the bag-shaped unit cell case has a power generation element housing part, a case welding part, and a gap portion therebetween, and has the largest width in the case welding part in contact with the gap part. Has a structure wider than a battery case width at a portion including a boundary between the gap portion and the power generation element housing portion.

Further, in the non-aqueous electrolyte secondary battery according to the present invention, a bag-shaped unit cell case having an airtight structure, an elliptical winding type power generating element having a winding center axis having an opening surface of the bag-shaped unit cell case. In a vertical direction.

Further, the nonaqueous electrolyte secondary battery according to the present invention is characterized in that the material of the bag-shaped unit cell case is a metal laminated resin film.

Further, in the non-aqueous electrolyte secondary battery according to the present invention, the widest part of the case welding portion in contact with the gap includes a battery in a portion including a boundary between the gap and the power generation element housing portion. It is characterized by being 0.1 mm or more wider than the case width.

Further, in the non-aqueous electrolyte secondary battery according to the present invention, the widest portion of the case welding portion in contact with the gap portion includes the battery at the portion including the boundary between the gap portion and the power generation element housing portion. It has a structure wider than the case width, and the length of the case welding portion is 0.2 mm or more and 15 mm
It is characterized by the following.

Further, in the non-aqueous electrolyte secondary battery according to the present invention, the widest part of the case welded portion in contact with the gap portion includes the boundary between the gap portion and the power generation element housing portion. It has a structure wider than the case width, and the thickness of the case welding portion is 0.03 mm or more and 1 mm
It is characterized by the following.

Further, the non-aqueous electrolyte secondary battery according to the present invention is characterized in that the battery weight is 4 g or more.

Further, the non-aqueous electrolyte secondary battery according to the present invention is characterized in that at least a part around the battery case does not have a case welded portion.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings, taking a battery provided with an elliptical winding type power generating element as an example. FIG. 1 shows an example of the appearance of a nonaqueous electrolyte secondary battery according to the present invention. In the case of this example, it corresponds to the widest part of the case welded portion in contact with the gap portion, the battery case width at the portion including the boundary between the gap portion and the power generation element housing portion, and the length of the case welded portion. The part is shown in FIG. 1 and 2, reference numeral 1 denotes a power generation element housing portion of a battery case, 2 denotes a welded portion of the battery case, 3 denotes a gap between the power generation element housing portion and the welded portion, 4 denotes a negative electrode lead terminal, and 5 denotes a positive electrode. It is a lead terminal.

In the non-aqueous electrolyte secondary battery according to the present invention, a power generating element is housed in a bag-shaped unit cell case, and the bag-shaped unit cell case has a power generating element housing part, a case welding part, and a gap between them. The widest part of the case welding portion in contact with the gap portion has a structure wider than the battery case width at a portion including the boundary between the gap portion and the power generation element housing portion.

In this specification, the battery case is described by dividing it into at least three parts: a power generation element housing part, a case welding part, and a gap between the power generation element housing part and the case welding part. However, the portion of the gap is,
In the space inside the battery case, it is a portion that forms a gap between the welded portion and the power generation element, and is a portion where the case is not directly in contact with the power generation element. The power generation element housing portion refers to a portion (excluding the welded portion) constituting a space in the battery case other than the gap portion. The present invention is effective even if the gap is extremely small.

The welded portion of the battery case serves as an impact-resistant material when a shock such as a drop is applied to the battery, and has an effect of suppressing damage to the power generating element. Therefore, the impact resistance of the battery can be improved by increasing the width of the welded portion of the battery case, but there is a problem that the energy density is reduced due to an increase in the volume and weight of the battery.
However, damage to the power generating element due to the impact concentrates on the corners.
Therefore, according to the present invention, the widest part of the case welded portion contacting the gap portion forms a boundary between the gap portion and the power generation element housing portion so that the case welded portion becomes larger only in the vicinity of the corner. This has a structure wider than the width of the battery case in the area including the battery case. Therefore, in the present invention, it is possible to significantly improve the impact resistance of the battery while suppressing a small decrease in the energy density due to an increase in the welded portion of the battery case.

In a conventional battery, when there is a portion without a case weld around the battery case, the impact resistance is greatly reduced due to the presence of a corner of the power generating element having no impact material. When the present invention is applied to such a battery, the widest part in the case welding part is slightly wider than the battery case width in a part including the boundary between the gap part and the power generation element housing part. Only by this, it is possible to prevent the impact from being directly transmitted to the corner of the power generation element, and it is possible to greatly improve the impact resistance of the battery.

When a metal foil and a resin film are bonded to a bag-shaped unit cell case, the battery can be stored in a smaller space by bending the welded portion. . In this case, the width of the welded portion and the width of the battery case are different before and after bending the welded portion, but the present invention is applied to both before and after bending the welded portion. By applying the present invention to a battery in a state before the welded portion is bent, it is possible to greatly reduce short-circuit failure of a corner portion of the battery due to a collision during a manufacturing process with a slight decrease in weight energy density. In addition, by applying the present invention to a battery in a state after the welded portion is bent, a slight decrease in volume energy density can cause a short-circuit failure of a battery corner used as a completed product and a risk of heat generation and smoking associated therewith. Properties can be greatly reduced.

The shape of the power generating element used in the present invention is not limited to an elliptical wound type in cross section, but may be a circular wound type, a non-circular wound type in cross section, or a flat plate-shaped electrode plate. A power generating element having any shape can be used, such as a stack type in which the sheet-shaped electrode plate is folded and a type in which the sheet-shaped electrode plate is folded and stacked through a separator.

In the present invention, a bag-shaped unit cell case having an airtight structure can be used, and a metal laminated resin film is preferably used as a material of the bag-shaped unit cell case.

In the present invention, when the elliptical wound type power generating element is stored in the bag-shaped unit cell case, the winding center axis of the elliptical wound type power generating element is set at the opening surface of the bag-shaped unit cell case. Preferably it is vertical. The vertical direction is
It does not only mean completely vertical, but also generally vertical.

As the metal material of the metal laminated resin film, aluminum, aluminum alloy, titanium foil, etc. can be used.

As the material of the heat-welded portion of the metal laminated resin film, any material may be used as long as it is a thermoplastic polymer material such as polyethylene, polypropylene, polyethylene terephthalate and the like.

Further, the resin layer and the metal foil layer of the metal laminated resin film are not limited to one layer each, but may be two or more layers.

The unit cell case may be a laminated case formed into an envelope by heat-sealing a metal-laminated resin film, a case in which four sides of two metal-laminated resin sheets are heat-sealed, or a single sheet. A metal-laminated resin film case of any shape can be used, such as a half-folded heat-sealed three-sided case, or a laminated case in which a power-generating element is placed in a metal-laminated resin sheet press-formed into a cup. it can.

The electrolyte solvent used for the nonaqueous electrolyte secondary battery according to the present invention includes ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, sulfolane, dimethyl sulfoxide, acetonitrile, dimethylformamide, dimethylacetamide. , 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran,
A polar solvent such as 2-methyltetrahydrofuran, dioxolan, methyl acetate, or a mixture thereof may be used.

The lithium salts dissolved in the organic solvent include LiPF6, LiClO4, LiBF4, LiA
sF6, LiCF3CO2, LiCF3SO3, LiN
(SO2CF3) 2, LiN (SO2CF2CF3)
2, LiN (COCF3) 2 and LiN (COCF2)
A salt such as CF3) 2 or a mixture thereof may be used.

As the separator of the non-aqueous electrolyte secondary battery according to the present invention, a separator in which an electrolytic solution is impregnated in an insulating polyethylene microporous membrane, a solid polymer electrolyte, or a solid polymer electrolyte containing an electrolytic solution is used. A gel electrolyte or the like may be used. Further, an insulating microporous film and a solid polymer electrolyte may be used in combination. Further, when a porous solid polymer electrolyte membrane is used as the solid polymer electrolyte, the electrolyte contained in the polymer and the electrolyte contained in the pores may be different.

Further, as a compound capable of inserting and extracting lithium as a positive electrode material, an inorganic compound is represented by a composition formula L
ixMO2 or LiyM2O4 (where M is a transition metal, 0 ≦ x ≦ 1, 0 ≦ y ≦ 2), a composite oxide, an oxide having tunnel-like vacancies, or a metal chalcogenide having a layered structure is used. be able to. Specific examples thereof include LiCoO2, LiNiO2, and LiMn2O.
4, Li2Mn2O4, MnO2, FeO2, V2O
5, V6O13, TiO2, TiS2 and the like.
Examples of the organic compound include a conductive polymer such as polyaniline. Further, the above-mentioned various active materials may be mixed and used regardless of an inorganic compound or an organic compound.

Further, as a compound as a negative electrode material, A
Alloys of lithium with l, Si, Pb, Sn, Zn, Cd, etc., transition metal oxides such as LiFe2O3, WO2, MoO2, carbonaceous materials such as graphite, carbon, Li5
Lithium nitride such as (Li3N) or metallic lithium foil, or a mixture thereof may be used.

The present invention is not limited to a secondary battery, but may be applied to a primary battery using lithium metal as a negative electrode active material and manganese oxide, carbon fluoride or thionyl chloride as a positive electrode active material. Good.

[0037]

Next, the present invention will be described based on preferred embodiments.

Embodiment 1 A non-aqueous electrolyte secondary battery according to the present invention uses a unit cell case in which a metal foil and a resin film are bonded to each other, and the battery case is composed of a power generation element housing part and a case welding part. And a gap portion therebetween, and the widest portion of the case welding portion in contact with the gap portion is wider than a battery case width at a portion including a boundary between the gap portion and the power generation element housing portion. It has a structure, and its appearance is shown in FIG.

As the positive electrode active material, a lithium cobalt composite oxide was used. The positive electrode plate is obtained by holding the above-mentioned lithium cobalt composite oxide as an active material on a current collector. An aluminum foil having a thickness of 20 μm was used for the current collector. The positive electrode plate was prepared by mixing 6 parts of polyvinylidene fluoride as a binder and 3 parts of acetylene black as a conductive agent together with 91 parts of an active material, appropriately adding N-methylpyrrolidone to prepare a paste, and then collecting the paste. It was manufactured by applying and drying both sides of an electric conductor material.

The negative electrode plate was prepared by mixing 92 parts of graphite (graphite) as a host substance and 8 parts of polyvinylidene fluoride as a binder on both sides of a current collector, and adding N-methylpyrrolidone as appropriate. Was prepared by coating and drying. A 14-μm-thick copper foil was used as the current collector of the negative electrode plate.

The separator was a microporous polyethylene membrane, and the electrolyte was a mixed solution of ethylene carbonate: diethyl carbonate = 4: 6 (volume ratio) containing 1 mol / l of LiPF6.

The dimensions of the electrode plate were such that the thickness of the positive electrode plate was 180 μm,
Width 49mm, separator thickness 25μm, width 53mm,
The negative electrode plate has a thickness of 170 μm and a width of 51 mm, and the lead terminals are welded to the positive electrode plate and the negative electrode plate, respectively, and are superposed one on the other, centering on a rectangular core of polyethylene, and the long side having a winding center axis of the power generating element. Was wound in an elliptical spiral shape around it so as to be in parallel with the above, to obtain a power generating element having a size of 53 × 35 × 4 mm.

Then, the insulating portion of the electrode is covered with an electrode width (length of the power generating element parallel to the winding central axis of the power generating element) by a tape for stopping winding made of polypropylene (here, an adhesive is applied to one side). Was attached to the side wall of the power generation element parallel to the winding center axis, and the power generation element was stopped and fixed.

This is accommodated in a metal-laminated resin film case, and the elliptical wound-type power generating element is housed so that the winding center axis is perpendicular to the opening surface of the bag-shaped metal-laminated resin film case, and the lead terminals are fixed. And seal the electrolyte.
Each electrode and the separator were sufficiently wetted, and vacuum injection was performed in such an amount that no free electrolyte solution was present outside the power generating element.

The laminated resin film uses a 12 μm PET film for surface protection as the outermost layer, a 9 μm aluminum foil as a barrier layer inside the PET film, and a 100 μm acid-modified low-density polyethylene layer as a heat welding layer as the innermost layer. . In this metal laminated resin film, the outermost PET film for surface protection and an aluminum foil as a barrier layer are bonded with a urethane-based adhesive. The positive lead terminal 5 and the negative lead terminal 4 have a thickness of 50 to 1
It is a metal conductor of copper, aluminum, nickel or the like of 00 μm.

Finally, sealing welding is performed to obtain a nominal capacity of 50 mm.
A 0 mAh laminated unit cell was prototyped. In addition, the widest part of the case welding portion that contacts the gap portion is 0.1, 0... 0, respectively, larger than the battery case width at the portion including the boundary between the gap portion and the power generation element housing portion.
Five types of batteries (A1), (A2) and (A3) according to the present invention having a structure of 5, 1.8 mm wide were manufactured.
In addition, a comparative battery having a structure in which the widest part of the case welding portion in contact with the gap portion is the same as the battery case width at a portion including the boundary between the gap portion and the power generation element housing portion ( B) was manufactured. Each of these batteries was manufactured in 20 pieces. In these batteries, the length of the case welds at both ends of the battery was 3 mm, the thickness was 0.25 mm, and the battery weight was about 12 g.

[0047] All of these manufactured batteries were 500
The battery was charged to 4.2 V at a constant current of mA, and
After a constant voltage charging for a time, a test was conducted in which the battery was dropped onto concrete 10 times from a height of 2 m. Table 1 shows the number of short-circuits and smoke generation among the 20 batteries subjected to this test.

[0048]

[Table 1]

From the results shown in Table 1, it can be seen that the battery according to the present invention is extremely unlikely to cause a short circuit and is extremely excellent in safety against dropping as compared with the comparative battery. Also, from Table 1, the width of the battery case at the part including the boundary between the gap and the power generation element storage part is 0.1 m with respect to the widest part of the case welded part in contact with the gap.
It can be seen that a sufficient short circuit and smoke prevention effect can be obtained when the width is wider than m.

[Embodiment 2] The length of the case welding portion is set to 0.
Batteries (C1), (C2), (C3), and (C4) according to the present invention in the same manner as the battery (A1) of the present invention in Example 1 except that they were 2, 1, 5, 15, and 25 mm. And (C5) were produced. Also, in the same manner as the comparative battery (B) in Example 1, except that the length of the case welded portion was 0.2, 1, 5, 15, and 25 mm, the comparative battery (D1), ( D2), (D3), (D4) and (D5) were produced. These batteries were all manufactured in 20 pieces.

[0051] All of these manufactured batteries are 500
The battery was charged to 4.2 V at a constant current of mA, and
After a constant voltage charging for a time, a test was conducted in which the battery was dropped onto concrete 10 times from a height of 2 m. Table 2 shows the number of short-circuits among the 20 batteries subjected to this test.

[0052]

[Table 2]

From the results shown in Table 2, it can be seen that the battery according to the present invention is very unlikely to cause a short circuit as compared with the comparative battery. From Table 2, it can be seen that the present invention is particularly effective when the length of the case welded portion is 0.2 mm or more and 15 mm or less. This result is because if the case welding portion is sufficiently long, the function of the welded portion as an impact buffering material is sufficient even in a conventional battery, and the possibility that an impact is applied to the corner portion is reduced. Conceivable. In the case of a battery having a case-welded portion having a length of less than 0.2 mm, a sufficient hermeticity was not obtained due to insufficient adhesive strength of the welded portion.

[Embodiment 3] The thickness of the case welding portion was set to 0.0
Except that it was 3, 0.1, 0.25, 1, 2 mm
In the same manner as in the battery (A1) of the present invention in Example 1,
Batteries (E1), (E2), (E3), (E)
4) and (E5) were produced. The comparative battery (B) was the same as the comparative battery (B) in Example 1 except that the thickness of the case welded portion was 0.03, 0.1, 0.25, 1, and 2 mm. F1), (F2), (F3),
(F4) and (F5) were produced. These batteries are
All 20 were produced.

[0055] All of these manufactured batteries were used for 500 hours.
The battery was charged to 4.2 V at a constant current of mA, and
After a constant voltage charging for a time, a test was conducted in which the battery was dropped onto concrete 10 times from a height of 2 m. Table 3 shows the number of short-circuits among the 20 batteries subjected to this test.

[0056]

[Table 3]

From the results shown in Table 3, it is understood that the battery according to the present invention is very unlikely to cause a short circuit as compared with the comparative battery. From Table 3, it can be seen that the present invention is particularly effective when the thickness of the case-welded portion is 0.03 mm or more and 1 mm or less. This result is considered to be because the function of the welded portion as a shock-absorbing material is sufficient even in a conventional battery when the case welded portion is sufficiently thick. In addition,
A battery with a case-welded portion having a thickness of less than 0.03 mm could not be assembled without damage due to insufficient material strength.

Example 4 The battery weight was changed by changing the width of the power generating element, the number of turns, the battery capacity, and the battery size.
Example 1 except that the weight was 50, 300 and 1500 g.
In the same manner as the battery (A1) of the present invention, the batteries (G1), (G2), (G3), (G4) and (G5) of the present invention were produced. In addition, the present invention has a structure other than that the widest part of the case welded portion in contact with the gap has the same structure as the battery case width in a portion including the boundary between the gap and the power generation element housing. Batteries (H1), (H2), (B1), (G2), (G3), (G4) and (G5) according to
(H3), (H4) and (H5) were produced. These batteries were all manufactured in 20 pieces. In these batteries, the length of the case-welded portions at both ends of the battery was 3 mm, and the thickness was 0.25 mm.

All of these batteries were charged at a constant current of 1 hour up to 4.2 V, and further charged at 4.2 V for 2 hours, and then charged on concrete at a height of 2 m. A drop test was performed. Table 4 shows the number of short-circuits among the 20 batteries subjected to this test.

[0060]

[Table 4]

From the results shown in Table 4, it can be seen that the battery according to the present invention is much less likely to cause a short circuit than the comparative battery. Table 4 shows that the present invention is particularly effective when the battery weight is 4 g or more. This is presumably because when the weight of the battery is light, the impact strength at the time of drop becomes weak, so that no short circuit occurs even in the conventional battery.

[0062]

According to the present invention, even when a metal foil laminated with a resin film is used for a battery case, the corner of the battery is damaged by an impact such as a drop or a collision, and an internal short circuit occurs. Can be suppressed. Therefore, temperature rise and smoke generation due to internal short circuit are suppressed,
The safety of the battery can be improved. In addition, even when the present invention is applied, the decrease in the energy density of the battery can be suppressed to a small amount.

[Brief description of the drawings]

FIG. 1 is an external view showing an example of a non-aqueous electrolyte secondary battery according to the present invention.

FIG. 2 shows an example of a non-aqueous electrolyte secondary battery according to the present invention, the widest part (A in FIG. 2) of a case welded part in contact with a gap, and a boundary between the gap and the power generation element housing part. , The width of the battery case at the site including (B in FIG. 2),
And a portion corresponding to the length of the portion of the gap (C in FIG. 2)
FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power generation element storage part of battery case 2 Battery case welding part 3 Gap part between power generation element storage part and welding part 4 Negative electrode terminal 5 Positive electrode terminal

Continuation of the front page (72) Inventor Tetsuya Murai 1 Inosibabacho, Nishinosho, Kichijoin, Kyoto, Kyoto, Japan Inside of Nippon Battery Co., Ltd. (72) Shinya Kitano Nishinosho, Nishinosho, Kyoto, Kyoto Nobabacho No. 1 Japan Battery Co., Ltd. (72) Hiroyuki Yumoto Inventor Hiroyuki Yumoto Kinoshoin Nishinosho Ino Babacho, Minami-ku, Kyoto, Kyoto 1 Japan Battery Co., Ltd. (72) Inventor Mikio Okada Kyoto, Minami Kyoto 1 Kishijo-in, Nishinosho-Inomabacho, Ward F-term (reference) in Nihon Batteries Co., Ltd. BJ02 BJ14 CJ05 DJ02 DJ04 DJ11 EJ01 EJ12 HJ01 HJ04

Claims (8)

[Claims] 1. A non-aqueous electrolyte secondary battery in which a power generating element having a positive electrode plate, a separator, and a negative electrode plate is housed in a bag-shaped unit cell case, wherein the bag-shaped unit cell case has a power generating element housing part and a case welding part. And a gap portion therebetween, and the widest portion of the case welding portion in contact with the gap portion is wider than a battery case width at a portion including a boundary between the gap portion and the power generation element housing portion. A non-aqueous electrolyte secondary battery having a structure. 2. A bag-shaped cell case having an airtight structure,
2. The non-aqueous electrolyte secondary battery according to claim 1, wherein the elliptical wound-type power generating element is housed such that a winding central axis thereof is perpendicular to an opening surface of the bag-shaped unit cell case. . 3. The non-aqueous electrolyte secondary battery according to claim 1, wherein the material of the bag-shaped unit cell case is a metal laminated resin film. 4. The widest part of the case welding portion in contact with the gap portion is 0.1 mm wider than the battery case width at a portion including the boundary between the gap portion and the power generation element housing portion.
The non-aqueous electrolyte secondary battery according to claim 1, wherein the secondary battery is 1 mm or more wide. 5. A structure in which a widest part of a case welding portion in contact with a gap portion has a structure wider than a battery case width at a portion including a boundary between the gap portion and a power generation element housing portion. The non-aqueous electrolyte secondary battery according to claim 1, wherein a length of the welded portion is 0.2 mm or more and 15 mm or less. 6. A case where a widest portion of a case welding portion in contact with a gap portion has a structure wider than a battery case width at a portion including a boundary between the gap portion and a power generation element housing portion. The non-aqueous electrolyte secondary battery according to claim 1, wherein the thickness of the welded portion is 0.03 mm or more and 1 mm or less. 7. The non-aqueous electrolyte secondary battery according to claim 1, wherein the battery weight is 4 g or more. 8. The non-aqueous electrolyte secondary battery according to claim 1, wherein a case welding portion does not exist in at least a part around the battery case.