JP2000294221A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-weight and safety nonaqueous electrolyte secondary battery. SOLUTION: In a nonaqueous electrolyte secondary battery comprising a generating element in a bag-shaped unit battery case, a thickness of a collector lead connected to a negative electrode plate and a collector lead connected to a positive electrode plate is 50 μm or more and 500 μm or less, a width thereof is 2 mm or more, the collector lead connected to the positive electrode plate is made of a metal of 100 kcal/(m.hr. deg.C) or more of heat conductivity, and the collector lead connected to the negative electrode plate is made of a metal of 70 kcal/(m.hr. deg.C) or more of heat conductivity, or the collector lead connected to the regulative electrode plate is made of a metal of 70 kcal/(m.hr. deg.C) or more of heat conductivity, and the collector lead connected to the positive electrode plate is made of a metal of 100 kcal/(m.hr. deg.C) or more of heat conductivity.

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 unit cells are housed in a bag-like 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 10 ₄ or LiPF ₆ 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.

The above-mentioned positive electrode plate, separator and negative electrode plate are each formed of a thin sheet or foil and laminated or spirally wound in order to form a battery container made of a metal laminated resin film having an airtight structure. Is stored in.

When this non-aqueous electrolyte secondary battery is used in electronic equipment, a desired voltage is obtained as a single battery or a plurality of batteries 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.

In recent years, as portable devices have been rapidly becoming smaller and lighter, demands for lighter, safer, and lower-priced batteries have been increasing not only for non-aqueous electrolyte batteries but also for devices powered by batteries. Never runs out. In order to reduce the size and weight of the battery, a laminated non-aqueous electrolyte unit cell is suitable and preferably has high safety.

[0007]

In a non-aqueous electrolyte secondary battery, a flammable organic compound is often used as a solvent for an electrolytic solution. Conventionally, the charge depth of lithium cobalt oxide used as a positive electrode active material is in a range of about 4.2 to 4.3 V with respect to the Li / Li ⁺ equilibrium potential. It is defined by the fact that the crystal structure of lithium can be reversibly maintained and the upper limit of the potential window of the electrolyte.

[0008] When the positive electrode potential continues to be charged beyond the above potential, the internal pressure of the battery increases due to the gas generated by the decomposition reaction of the organic electrolyte solution or the decomposition reaction of the positive electrode active material, and the battery temperature increases due to the reaction heat. Cause the battery to rupture,
It will catch fire.

For this reason, in a non-aqueous electrolyte battery, a protection circuit is provided to ensure the safety of the battery so that the positive electrode potential does not exceed a specified potential before the battery explodes or ignites. Furthermore, it is desirable that the safety of the battery can be ensured even when the protection circuit breaks down due to some cause and becomes overcharged.

As one of the causes of the explosion and ignition of the non-aqueous electrolyte secondary battery during overcharge, various exothermic reactions which occur in a chain in the non-aqueous electrolyte battery are considered.
That is, when the nonaqueous electrolyte battery is overcharged, the battery temperature rises due to heat generated by the electrolytic solution decomposition reaction. When the battery temperature reaches about 120 ° C., it is considered that the heat generated by the decomposition reaction of the film on the graphite surface used for the negative electrode and the electrolytic solution decomposition reaction on the graphite surface accelerate the temperature rise of the battery. These reactions cause boiling of the electrolytic solution, expansion of the gas already existing in the battery, and the like, and there is a problem that the internal pressure of the battery rapidly increases.

If these exothermic reactions proceed in an adiabatic state, it is considered that the battery temperature causes thermal runaway due to the self-decomposition reaction of the positive electrode active material, leading to rupture or ignition of the battery.

[0012] Therefore, as a means for solving the above-described problems such as bursting and ignition of the non-aqueous electrolyte battery,
In addition to the means of suppressing individual exothermic reactions that cause these batteries to increase in temperature, the heat generated inside the batteries is effectively released outside the batteries so that the battery temperature does not rise to the temperature at which heat escapes. Must.

Here, a unit cell using a battery case formed by heat-welding a metal laminated resin film (hereinafter abbreviated as “laminated unit cell”) is compared with a unit cell using a conventional metal battery case. Therefore, when heat is generated in the battery due to the small thermal conductivity of the case itself, heat is not easily radiated through the case.

Further, when gas is generated in the battery, the laminated unit cell is easily expanded and deformed, and a gap is formed between the power generating element and the battery case. It is considered that the gas layer between the power generating element and the metal laminated resin film case acts as a heat insulating layer, and the heat generated in the power generating element cannot be effectively conducted to the battery case and cannot be dissipated.

As a result, when gas is generated at the time of overcharging and the battery thickness increases, the temperature of the power generating element is more likely to rise in the laminated unit cell than in the unit cell using the metal case. It is thought to be.

That is, at the time of overcharging of the laminated unit cell, it is very important to suppress the above-mentioned chain-wise exothermic reactions themselves and to effectively release the heat generated thereby to the outside of the battery system. It is thought that it becomes important to.

For the purpose of ensuring the safety of the non-aqueous electrolyte battery at the time of overcharging, the use of an electrolyte additive that decomposes when the positive electrode potential reaches about 4.6 V makes it possible to charge the positive electrode active material. A method has been proposed that suppresses the decomposition and exothermic reaction of the positive electrode active material at a high potential without further progressing the reaction. However, depending on this method, it is left at a lower voltage or at a higher temperature than a conventional nonaqueous electrolyte battery. Occasionally, a gas is generated due to decomposition of the electrolyte additive.

For this reason, it is not preferable to use this method for a laminated unit cell in which battery expansion and deformation are likely to occur. This is because, when the laminated cell is expanded and deformed by the decomposition gas of the electrolytic solution, the power generation element is hardly dissipated as described above, causing an exothermic reaction due to decomposition of the film of the negative electrode, and subsequently causing thermal runaway of the positive electrode active material.

[0019]

SUMMARY OF THE INVENTION A non-aqueous electrolyte battery according to the present invention has been made in view of the above problems, and has a bag-shaped unit cell case, a power generating element having a positive electrode plate, an isolator, and a negative electrode plate. In the non-aqueous electrolyte secondary battery containing the battery, the thickness of the current collecting lead joined to the negative electrode plate and the current collecting lead joined to the positive electrode plate is 50 μm or more and 500 μm or less, and the width is 2 mm.
As described above, the current collecting lead bonded to the positive electrode plate has a thermal conductivity of 1
A metal of at least 00 kcal / (m · hr · ° C.)
The current collecting lead bonded to the negative electrode plate has a thermal conductivity of 70 kcal
/ (M · hr · ° C.) or more, or the current collecting lead bonded to the negative electrode plate has a thermal conductivity of 70 kcal /
(M · hr · ° C.) or more, and the current collecting lead bonded to the positive electrode plate has a thermal conductivity of 100 kcal / (m · h).
(r.degree. C.) or higher.

Further, the present invention is characterized in that the material of the bag-shaped unit cell case is a metal laminated resin film.

According to the present invention, even when the laminated unit cell expands and deforms and heat radiation of the power generating element is not effectively performed through the battery case, heat generated in the positive electrode plate and the negative electrode plate is transferred to the outside of the battery system through the leads. To effectively suppress the rise in the battery temperature and suppress the thermal runaway of the positive electrode active material, which is the next exothermic reaction.

According to the present invention, in a nonaqueous electrolyte secondary battery using a metal laminated resin film case, the weight energy density can be improved as compared with a conventional metal case, and this laminated unit cell can be made safe. be able to.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION A non-aqueous electrolyte secondary battery according to the present invention comprises a power generating element or a sheet-like electrode formed by laminating a large number of flat electrodes formed into a foil shape via an isolator. The wound power generating element is housed in a bag-shaped unit cell case, and the metal leads joined to the negative and positive plates of the power generating element are taken out from the heat-welded part of the bag-shaped unit cell case. is there. In particular, as the material of the cell case,
Use a metal laminated resin film.

The current collecting lead joined to the negative electrode plate and the current collecting lead joined to the positive electrode plate have a thickness of 50 μm to 500 μm and a width of 2 mm or more. When the thickness of the lead is less than 50 μm, the mechanical strength is too small to be used when joining the lead to other equipment, and when the thickness of the lead exceeds 500 μm, the heat welding of the lead portion occurs. In some cases, sealing is difficult and sealing cannot be performed, and the weight of the lead portion also increases, lowering the energy density of the battery.

When the width of the lead is less than 2 mm,
The electric resistance is increased, which is disadvantageous in charging and discharging with a large current, and furthermore, handling becomes difficult. Further, the maximum value of the lead width is limited by the length of the sealing portion of the lead attachment portion. That is, if the width of the lead is too large with respect to the length of the sealing portion, the heat-welded portion of the sealing portion is shortened, and the sealing portion is easily peeled. Therefore, when the length of the sealing portion of the lead attachment portion is Lmm, since the positive electrode lead and the negative electrode lead are attached to this sealing portion,
Although the width of each lead cannot be set to L / 2 mm or more, it is preferable to set the width of the lead to 3L / 8 or less in order to prevent peeling of the thermal welding at the sealing portion.

The current collecting lead joined to the positive electrode plate is made of a metal having a thermal conductivity of 100 kcal / (m · hr · ° C.) or more, or the current collecting lead joined to the negative electrode plate has a thermal conductivity of 7 or more.
A metal of 0 kcal / (m · hr · ° C.) or more, or a metal having a thermal conductivity of 70 kcal / (m · hr · ° C.) or more as a current collecting lead bonded to the negative electrode plate; A non-aqueous electrolyte secondary battery using a bag-shaped unit cell case according to the present invention by using a metal having a thermal conductivity of 100 kcal / (m · hr · ° C.) or more as a current collecting lead bonded to a positive electrode plate When some kind of heat is generated in the battery, the heat can be effectively released to the outside of the battery through the lead, so that the safety at the time of overcharging is enhanced.

According to the present invention, since the power generation element is housed in a thin sheet-like soft case such as a metal laminated resin film, the air-tightness is excellent, the complexity of the sealing process can be eliminated, and the cost can be reduced. Production and weight reduction are possible.

In addition, since the cells have excellent airtightness, the airtightness of the hard case itself does not matter as in the conventional case. Therefore, since a one-touch assembly structure can be provided, the manufacture of the battery pack can be extremely facilitated. Furthermore, since the terminal for connecting external devices formed by insert molding is formed in the battery housing, the manufacturing process can be further simplified and the manufacturing cost can be further reduced.

In the present invention, polyethylene has been described as an example of the material of the heat-welded portion of the metal laminate resin film, but a thermoplastic polymer material such as polypropylene or polyethylene terephthalate can be used.

Examples of the bag-shaped unit cell case include 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, and a single sheet. Use a metal-laminated resin film case of any shape, such as one obtained by folding the sheet in two and heat-welding the three sides, or a laminating case in which a power-generating element is placed in a cup-shaped metal-laminated resin sheet. be able to.

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.

Examples of lithium salts dissolved in an organic solvent include LiPF ₆ , LiClO ₄ , LiBF ₄ , and LiAs.
F ₆ , LiCF ₃ CO ₂ , LiCF ₃ SO ₃ , LiN (SO ₂
CF ₃ ) ₂ , LiN (SO ₂ CF ₂ CF ₃ ) ₂ , LiN (CO
Salts such as CF ₃ ) ₂ and LiN (COCF ₂ CF ₃ ) ₂ or mixtures thereof may be used.

As the separator of the non-aqueous electrolyte secondary battery according to the north invention, an insulating solution obtained by impregnating an insulating microporous polyethylene film with an electrolyte, a solid polymer electrolyte, or a solid polymer electrolyte may be 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
i _x MO ₂ or Li _y M ₂ O _4, (where M is a transition metal,
A composite oxide represented by 0 ≦ x ≦ 1, 0 ≦ y ≦ 2),
An oxide having tunnel-like holes and a metal chalcogenide having a layered structure can be used. As specific examples, LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , Li
₂ Mn ₂ O ₄ , MnO ₂ , FeO ₂ , V ₂ O ₅ , V ₆ O ₁₃ , T
iO ₂ , TiS _{2 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 LiFe ₂ O ₃ , WO ₂ , MoO ₂ , graphite, carbonaceous materials such as carbon, Li
Lithium nitride such as ₅ (Li ₃ N), or metallic lithium foil, or a mixture thereof may be used.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described based on preferred embodiments with reference to the drawings. Embodiment 1 FIG. 1 is a view showing the appearance of a non-aqueous electrolyte secondary battery according to the present invention. In FIG. 1, reference numeral 1 denotes a nonaqueous electrolyte secondary battery, 2 denotes a metal laminated resin film case, 3 and 4 denote heat-welded portions of the metal laminated resin film case, 5 denotes a positive electrode lead, and 6 denotes a negative electrode lead. An electrode group consisting of a positive electrode plate, a separator, and a negative electrode plate was housed in a laminated film case 2 formed by heat-welding a metal laminated resin film together with a non-aqueous electrolyte (not shown).

As the positive electrode active material, a lithium cobalt composite oxide was used. The positive electrode plate has a current collector in which the above-described lithium cobalt composite oxide is held as an active material. The current collector is an aluminum foil having a thickness of 20 μm. 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,
It was prepared by adding N-methylpyrrolidone appropriately to prepare a paste, and then applying and drying both surfaces of the current collector material. The dimensions of the positive electrode lead are 3 mm in width and 10 in thickness
0 μm, and the length of the portion protruding outside the case was 10 mm.

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. The current collector of the negative electrode plate has a thickness of 1
4 μm copper foil was used. The dimensions of the negative electrode lead are 3 mm wide,
Thickness 100μm, length 1 of the part outside the case
0 mm.

The separator was a microporous polyethylene membrane, and the electrolyte was a mixed solution of ethylene carbonate: diethyl carbonate = 3: 7 (volume ratio) containing 1 mol / l of LiPF ₆ .

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.
After being wound in an elliptical shape around it, it was stored in a metal laminated resin film case.

FIG. 2 is a cross-sectional view of the non-aqueous electrolyte secondary battery shown in FIG. In FIG. 2, 5
Is a positive electrode lead, 6 is a negative electrode lead, 10 is a 12 μm thick polyethylene terephthalate (P) for protecting the surface of the outermost layer.
ET) film, 11 is an aluminum foil having a thickness of 9 μm as a barrier layer, and 12 is 100 μm as a heat welding layer.
m, which is an acid-modified polyethylene (PE) layer, the laminated film case for the hermetic opening is composed of 10, 11, and 12, and the outermost surface protective PET film 10 and the aluminum foil 11 as the barrier layer are a urethane-based adhesive. Glued.

In FIG. 2, reference numeral 13 denotes an adhesive layer;
Denotes an electrolyte barrier layer, and the positive electrode lead 5 and the negative electrode lead 6 adhere to a 100 μm acid-modified medium density polyethylene layer forming an adhesive layer 13 with a metal, and have a 70 μm evar as an electrolyte barrier layer 14 outside thereof. A resin (ethylene-vinyl alcohol copolymer resin manufactured by Kuraray) layer is provided. When these are superposed and adhered as shown in FIG. 2, good airtightness can be obtained.

As a lead material, a battery using aluminum for the positive electrode and copper for the negative electrode was designated as No. 1-1, a battery using nickel-plated copper for the positive electrode and copper for the negative electrode was designated as No. 1; 1-
No. 2, batteries using aluminum for the positive electrode and nickel for the negative electrode No. 1-3, a battery using aluminum for the positive electrode and stainless steel (SUS304) for the negative electrode was designated as No. 1-3.
Nos. 1-4, batteries using aluminum for the positive electrode and titanium for the negative electrode were designated as Nos. 1-4. No. 1-5, a battery using nickel for the positive electrode and copper for the negative electrode was designated as No. 1; 1-6.

In this manner, a trial production of a laminated unit cell having a nominal capacity of 500 mAh was made. Example 2 A laminated unit cell similar to that of Example 1 was manufactured except that the materials of the metal forming the positive electrode lead and the negative electrode lead were different.

As a lead material, a battery using nickel for the positive electrode and nickel for the negative electrode was No. No. 2-1. A battery using nickel for the positive electrode and stainless steel (SUS304) for the negative electrode was designated as No. 2. No. 2-2, a battery using nickel for the positive electrode and titanium for the negative electrode was designated as No. 2. 3-3. [Example 3] Battery No. 1 of Example 1 was different except that the widths of the positive electrode lead and the negative electrode lead were different. A laminated unit cell similar to 1-1 was manufactured.

A battery having a lead width of 1.5 mm for both the positive and negative electrodes was designated as No. Nos. 3-1 and 2 mm were used for the batteries. 3
-2, 2.5 mm batteries 3-3. Example 4 Battery No. 1 of Example 1 was different except that the thicknesses of the positive electrode lead and the negative electrode lead were different. A laminated unit cell similar to 1-1 was manufactured.

A battery having a lead thickness of 40 μm for both the positive and negative electrodes was designated as No. Nos. 4-1 and 50 μm,
No. 4-2, the battery of 500 μm was designated as No. 4-3, 520
No. of the battery having the size of μm. 4-4.

To compare the safety of the laminated single batteries of Examples 1 to 4, overcharging was performed at 25 ° C. to 1 A / 10 V. Table 1 shows the results.

[0049]

[Table 1]

Note: The unit of the thermal conductivity is kcal / (mh
・ R ・ ℃) From Table 1, No. 1-1 to 1-6, 3-2, 3-3, 4
The batteries Nos. -1 to 4-3 are described in Example Nos. 2-1 to 2-3,
It turns out that the safety at the time of overcharge is superior to the batteries 3-1 and 4-4.

Here, in order to clarify the cause of the above result, the embodiment No. 1-1 to 4-4 batteries,
The batteries were charged at a current of 1 A, and when the terminal voltage reached 5.8 V, charging was stopped, and disassembly inspection of these batteries was performed in a dry atmosphere.

As a result, Example No. 1-1 to 1-6,
In the battery elements of Nos. 3-2, 3-3, and 4-1 to 4-4, the separator maintained the same white color as when the battery was manufactured. In 2-1 to 2-3 and 3-1, the separator facing the vicinity of the negative electrode lead was discolored to be transparent. In Example 2-3, the separator facing the vicinity of the positive electrode lead was discolored to be transparent.

Such discoloration of the separator suggests that the battery temperature once increased to near the melting point of the separator during overcharge. That is, Example No. 2-1 to 2
In the batteries of -3 and 3-1, the heat conductivity of the positive electrode lead or the negative electrode lead was low, and the heat generation rate in the battery was higher than the rate of heat radiation performed by the leads.
Example No. 1-1 to 1-6, 3-2, 3-3, 4-1
It is considered that the battery temperature increased as compared with the batteries of Nos. 4-4. For this reason, in Example No. 2-1 to 2-
In the batteries of Nos. 3 and 3-1, it is presumed that the battery temperature reached the self-decomposition temperature of the positive electrode active material and caused thermal runaway, resulting in low safety during overcharge.

In addition, No. The battery of No. 4-4 had no problem with the heat conduction of the lead, but the battery was ruptured even with a slight increase in the internal pressure because the length of the heat-welded portion was insufficient. Also,
No. The battery of 4-1 did not have any problem in the overcharge test, but the mechanical strength of the lead portion was weak, causing a problem in handling and connection with other devices.

As described above, the thickness of the negative electrode lead and the positive electrode lead is 50 μm or more and 500 μm or less, the width is 2 mm or more, and the thermal conductivity of the positive electrode lead is 100 kcal /
(Mh.r..degree. C.) or more and the thermal conductivity of the negative electrode lead is 7
It was found that a non-aqueous electrolyte secondary battery having excellent safety at the time of overcharging can be obtained when it is 0 kcal / (mh · r · ° C.) or more.

[0056]

By using the positive electrode lead and the negative electrode lead according to the present invention, when heat is generated inside the battery, the heat is effectively released to the outside of the battery via the lead, so that the safety of the battery is improved. Therefore, the weight and thickness of the nonaqueous electrolyte battery can be reduced, which is useful as a component of a portable electronic device.

[Brief description of the drawings]

FIG. 1 is a diagram showing the appearance of a non-aqueous electrolyte secondary battery according to the present invention.

FIG. 2 is a sectional view taken along line AA ′ of the nonaqueous electrolyte secondary battery according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Non-aqueous electrolyte secondary battery 2 Metal laminated resin film case 3, 4 Heat-welded part of metal laminated resin film case 5 Positive electrode lead 6 Negative electrode lead

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) EJ11 HJ00 HJ04

Claims (4)

[Claims] 1. A non-aqueous electrolyte secondary battery in which a power generating element having a positive electrode plate, an isolator, and a negative electrode plate is housed in a bag-shaped unit cell case, and joined to a current collecting lead and a positive electrode plate joined to the negative electrode plate. The thickness of the current collecting lead is 50 μm or more and 500 μm
m and a width of 2 mm or more, and the current collecting lead joined to the positive electrode plate has a thermal conductivity of 100 kcal / (m · hr ·
C) or higher metal. 2. A non-aqueous electrolyte secondary battery in which a power generation element having a positive electrode plate, an isolator, and a negative electrode plate is housed in a bag-shaped unit cell case, and joined to a current collecting lead and a positive electrode plate joined to the negative electrode plate. The thickness of the current collecting lead is 50 μm or more and 500 μm
m and a width of 2 mm or more, and the current collecting lead bonded to the negative electrode plate has a thermal conductivity of 70 kcal / (m · hr · ° C.).
A non-aqueous electrolyte secondary battery comprising the above metal. 3. A non-aqueous electrolyte secondary battery in which a power generation element having a positive electrode plate, a separator, and a negative electrode plate is housed in a bag-shaped unit cell case, and joined to a current collecting lead and a positive electrode plate joined to the negative electrode plate. The thickness of the current collecting lead is 50 μm or more and 500 μm
m and a width of 2 mm or more, and the current collecting lead bonded to the negative electrode plate has a thermal conductivity of 70 kcal / (m · hr · ° C.).
A non-aqueous electrolyte secondary battery comprising the above metal, and the current collecting lead bonded to the positive electrode plate is a metal having a thermal conductivity of 100 kcal / (m · hr · ° C.) or more. 4. The material of the bag-shaped unit cell case is a metal laminated resin film.
The nonaqueous electrolyte secondary battery according to the above.