JP2003282143A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery with excellent safety capable of preventing a battery case from expanding or exploding by deriving generated gas from an electrode group even if the electrode group expands due to gas generation. <P>SOLUTION: This nonaqueous electrolyte secondary battery including the columnar electrode group in which a strip negative electrode, a separator and a strip positive electrode are sequentially laminated, a nonaqueous electrolytic solution impregnated into the separator, and the columnar battery case housing the electrode group and the nonaqueous electrolyte has a spacer for forming a grooved uneven part between the electrode group and the battery case in the parallel direction with the axis of the electrode group. Letting L<SB>1</SB>denote the length of the spacer, and L<SB>2</SB>denote the height of the electrode group, the ratio L<SB>1</SB>/L<SB>2</SB>is 0.33-0.99. <P>COPYRIGHT: (C)2004,JPO

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, and more particularly to a high power type non-aqueous electrolyte secondary battery with improved safety.

[0002]

2. Description of the Related Art In recent years, lithium ion secondary batteries and polymer lithium secondary batteries using non-aqueous electrolytes have been widely used in electronic devices such as mobile phones. These secondary batteries are characterized by being lighter in weight than conventional nickel-cadmium batteries and nickel-hydrogen batteries and having high electromotive force of 4 V class, and their excellent performance is drawing attention.

Therefore, recently, application of this lithium secondary battery as a power source for electric vehicles (EVs), electric tools, cordless cleaners, etc. has been studied. In such applications, higher output characteristics are required as compared with conventional lithium secondary batteries.

In order to increase the output of a battery, it is necessary to reduce the internal resistance of the battery as much as possible. For that purpose, it is important to reduce the resistance of the electrode and the battery member and enhance the current collecting efficiency. As one of the measures, development of a cylindrical lithium secondary battery or a rectangular lithium secondary battery in which electrodes have a plurality of current collecting leads is under way. With such a configuration, current collection efficiency is improved and internal resistance of the battery can be reduced, so that a battery having excellent output characteristics can be formed. Further, in such a high-power type lithium secondary battery, since charging can be performed with a large current, rapid charging is possible.

Generally, lithium secondary batteries are not only safe in normal use, but also have abnormal battery internal pressure due to improper handling such as overcharging, external short circuit, or leaving in a high temperature atmosphere for a long time. There is a strong demand for safety when climbing. As a safety measure, the lithium secondary battery is equipped with a safety valve that operates by the internal pressure of the battery, i.e., an explosion-proof valve, which cleaves when the internal pressure exceeds a specified value and releases the gas filled inside the battery container to the outside. This prevents the battery from bursting.

However, in the high-power type lithium secondary battery as described above, charging / discharging with a large current is possible, but on the other hand, when an abnormality such as overcharging occurs, it occurs due to decomposition of the electrolytic solution or the like. The generated gas is likely to stay inside the battery container, the filled gas is not quickly released to the outside, and problems such as swelling and rupture of the battery container may occur.

In order to avoid such a situation, in a large cylindrical lithium ion secondary battery having a battery capacity of 30 Ah or more, which is suitable for a power source for EV, it is made of a resin having an electrically insulating property, The electrode winding group is arranged between the electrode winding group and in the vicinity of both ends of the electrode winding group, and the electrode winding group is wound around the outer circumference of the electrode winding group by the gas pressure generated inside the electrode winding group. A cylindrical lithium ion battery is proposed, which is provided with a spacer surrounding a circular arc in which a gap having a predetermined interval is formed to allow expansion in the diameter direction of the swarm, and Japanese Patent Laid-Open No. 2001-143759 discloses It is disclosed. In this battery, when gas pressure is generated inside the electrode winding group at the time of abnormality, the generated gas expands both ends of the electrode winding group in the diameter direction of the electrode winding group to smoothly wind the electrode winding group from both ends. It is discharged to the outside of the group. The gas discharged from both ends of the electrode winding group is discharged from the explosion-proof valve to the outside of the battery when the internal pressure of the battery container reaches a predetermined pressure. Therefore, it is disclosed that the battery safety can be ensured because abnormal heat generation in the battery container and significant deformation of the battery container are not caused.

However, this lithium-ion battery has a structure in which the spacers are arranged only near the upper and lower end portions of the electrode winding group. Therefore, when a gas pressure is generated inside the electrode winding group at the time of abnormality, it is generated. The gas expands the central part of the electrode winding group where the spacer is not arranged the largest in the diameter direction of the electrode winding group, and as a result, the space between the battery container and the central part of the electrode winding group is damaged. In some cases, the gas may stay inside the battery container without being discharged from the explosion-proof valve, and the central part of the battery container may expand and deform, causing a rupture. This phenomenon is particularly remarkable when this spacer is applied to a cylindrical lithium ion secondary battery having a structure in which a battery upper lid is caulked and sealed in a bottomed cylindrical battery container (can).

[0009]

In the conventional lithium secondary battery, since the spacer is not present in the center of the electrode group, gas generation is most noticeable due to gas generation, and the central portion of the battery swells to lead out gas. Could not be secured, and there was a risk of swelling or rupture of the battery container.

The present invention has been made in view of the above problems. Even when the electrode group expands due to gas generation, the generated gas is led out from the electrode group to prevent the battery container from swelling or rupturing. An object of the present invention is to provide a non-aqueous electrolyte secondary battery having excellent preventive safety.

[0011]

[Means for Solving the Problems] To solve the above problems
The non-aqueous electrolyte secondary battery according to claim 1 has a strip negative electrode and a separator.
A columnar electrode group in which a battery and a strip positive electrode are sequentially laminated,
The non-aqueous electrolyte solution impregnated in the separator, the electrode group and
And a columnar battery container containing the non-aqueous electrolyte.
In the non-aqueous electrolyte secondary battery, the electrode group and the battery
A groove-shaped recess between the containers and in the direction parallel to the axis of the electrode group.
A spacer forming a convex portion, and the height of the electrode group
The length of the spacer parallel to the direction is L₁, Of the electrode group
Height is L₂Then, the ratio L₁/ L₂Is 0.33 or more,
It is characterized by being 0.99 or less. Length ratio L₁/ L₂
0.33 ≦ L₁/ L₂≤0.99 is defined as long
Ratio L ₁/ L₂Is less than 0.33, before the electrode group
The area where the sheet is not placed expanded in the diameter direction of the electrode group.
Space between the battery container and the center of the electrode group
Is damaged and the generated gas is not discharged from the explosion-proof valve
When the battery container is deformed by staying near the bottom of the pond container
It is not preferable because there is a possibility that Well
Also, when it exceeds 0.99, it is generated from near the bottom of the electrode group.
Gas is not discharged to the outside of the electrode group and stays inside the electrode group.
Scratch, resulting in swelling or bursting of the battery container.
Because it is rugged.

According to a second aspect of the non-aqueous electrolyte secondary battery of the first aspect, the ratio L ₁ / L ₂ is 0.83 or less.

According to a third aspect of the present invention, in the non-aqueous electrolyte secondary battery according to the first aspect, the spacer has a plurality of rod-shaped components formed on the outer periphery of the electrode group.

A non-aqueous electrolyte secondary battery according to a fourth aspect is characterized in that, in the first aspect, the spacer is a processed product in which a metal plate is bent to form the groove-shaped irregularities.

According to a fifth aspect of the non-aqueous electrolyte secondary battery of the first aspect, the spacer is fixed to the outermost peripheral surface of the electrode group with an adhesive material.
In this case, since it is not necessary to increase the number of parts loaded and the manufacturing process does not need to be changed, it is possible to secure battery safety while suppressing cost increase.

The electrode group of the present invention is preferably a spiral electrode group formed by spirally winding an electrode group in which a strip-shaped negative electrode, a separator and a strip-shaped positive electrode are sequentially laminated, and in this case, the battery shape is a cylindrical shape. However, it may be a polygonal prism such as a square prism or a hexagonal prism. Further, it may have a multiple stacked electrode group structure in which a plurality of stacked electrode groups are further stacked, and in this case, the battery shape is preferably a polygonal prism, for example, a quadrangular prism.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a non-aqueous electrolyte secondary battery according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 5. (Embodiment of 1st invention) a) Spacer First, the spacer in which the groove-shaped uneven | corrugated part was formed in the surface is demonstrated using FIG. In FIG. 1, FIG. 1A is a developed view of the spacer, and FIG. 1B is a vertical sectional view thereof. Reference numeral 2A is a support of a sheet on which uneven portions are formed, the convex portions 1 are formed on the front surface thereof, and the adhesive material 2B is applied to the back surface thereof. As the support 2A,
A material having sufficient chemical and physical stability to the organic electrolyte is used. Specifically, paper, styrene-
Examples thereof include butadiene rubber, polyethylene, polypropylene, polyimide, polyester, and fluorine resin.

As the adhesive material 2B, an acrylic adhesive, a silicone adhesive or the like can be used.

Reference numeral 3 is a groove-shaped recess. This groove-shaped recess 3
Are preferably evenly spaced on the support 2A. Although FIG. 1 shows an example in which the groove-shaped recess has a trapezoidal shape, other shapes such as a rectangular shape, a triangular shape, and an arc shape can be cited, but the shape is not particularly limited.

In this spacer, the total thickness including the adhesive material layer 2B is preferably in the range of 100 μm or more and 250 μm or less.

The groove-shaped recess 3 has a depth of 50 μm to 20 μm.
The range is preferably 0 μm.

The thickness of the adhesive material layer 2B is 15 μm to 30 μm.
It is preferably set to μm.

Further, this spacer also serves as an adhesive tape for fixing the winding end portion of the spiral electrode group. In this case, the adhesive material layer 2B is a polyethylene tape,
It is preferable to use polypropylene tape, polyimide tape, polyester tape, fluororesin tape, or the like.

FIG. 2 is a circumferential sectional view showing the spacer fixed to the outermost circumference of the spiral electrode group 4. 2A is arranged so that the groove-shaped recess 3 is in contact with the battery container 5, and FIG. 2B is so arranged that the groove-shaped recess 3 is in contact with the electrode group 4. 2C is an adhesive material layer for being fixed to the electrode group 4. In addition, it is preferable that the groove-shaped concave portion 3 is provided on the entire outermost circumference of the spiral electrode group 4. in this case,
The gas flow path is secured around the entire circumference of the spiral electrode group 4. The adhesive material layer may also be formed between the support 2A and the battery container 5.

FIG. 3 shows a spacer having an uneven portion,
FIG. 3 is a schematic perspective view showing the spiral electrode group 4 fixed to the outermost periphery. In this case, the spacer having the concavo-convex portion is arranged at the outermost periphery of the spiral electrode group 4 in the center in the height direction, and the spacer of the spiral electrode group 4 of the sheet having the concavo-convex portion is formed. Assuming that the length along the height direction is L ₁ and the height of the spiral electrode group 4 is L ₂ , the length ratio L ₁ / L ₂
Is set to 0.67 ≦ L ₁ / L ₂ ≦ 0.99.
Further, the upper part 31 and the lower part 32 of the electrode group have a uniform height, but this height does not have to be uniform, and the upper part 3
The ratio of the height of the lower portion 32 to the height of 1 is 0.5 or more,
It is preferably 2 or less.

Next, another structure of the non-aqueous electrolyte secondary battery according to this embodiment will be described with reference to FIG.

For example, a bottomed cylindrical container 5 made of nickel-plated iron has an insulator 6 at the bottom. The spiral electrode group 4 is housed in a battery container 5. The spiral electrode group 4 has a structure in which a band-shaped material in which a positive electrode 7, a separator 8 and a negative electrode 9 are laminated in this order is spirally wound so that the negative electrode 9 is located outside. Separator 8
Is formed of, for example, a non-woven fabric, a polypropylene microporous film, a polyethylene microporous film, or a polyethylene-polypropylene microporous laminated film.

The battery container 5 contains an electrolytic solution. Safety valve 11 having a valve membrane portion 10 in the central portion, safety valve 1
1, a hat-shaped positive electrode terminal 12 and a battery container 5 arranged on
Is caulked and fixed to the upper opening of the via an insulating gasket 13. The positive electrode terminal 12 has a gas vent hole 14
It is open. One end of the positive electrode lead 15 is connected to the positive electrode 7,
The other ends are connected to the safety valve 11, respectively, and when the internal pressure of the battery rises, the valve membrane part 10 bulges and deforms to separate the welded part and interrupt the current. The negative electrode 9 is connected to the battery container 5 serving as a negative electrode terminal via a negative electrode lead 16.

Next, the positive electrode 7, the negative electrode 9 and the electrolytic solution will be specifically described. b) Positive Electrode 7 The positive electrode 7 is produced, for example, by applying a positive electrode material paste obtained by dispersing a positive electrode active material, a conductive agent and a binder in a suitable solvent to one side or both sides of a current collector.

As the positive electrode active material, LiCoO ₂ or composition formulas LiCo _1-x M _x O ₂ and LiNi _1-x M _x O ₂ (wherein, M is one or more elements, and x is 0 <x ≤ 0.5
Of the above) can be used. Specifically, LiCo _1-x Ni _x O ₂ , Li
Ni _1-x Co _x O ₂ , LiNi _1-xy Co _x Al _y O ₂ , Li
_{Ni 1-xy Co x Mn y} O 2 , and the like. (Where x and y are 0 <x ≦ 0.5, 0 ≦ y <0.5, and 0 <
x + y ≦ 0.5) Further, a mixture of two or more kinds of these lithium mixed metal oxides may be used.

As the positive electrode active material, a mixture of lithium nickel composite metal oxide and spinel type lithium manganese oxide can be used.

As the lithium composite oxide, LiNiO
₂, LiNi_0.7Co_0.3O₂, LiCo_0.8Ni_0.2O₂,
Li_1.075Ni_0.755Co_0.17O_1.9F_0.1, Li_1.10Ni
_0.74Co_0.16O_1.85F_0.15, Li_1.075Ni_0.705Co
_0.17Al_0.05O_1.9F_0.1, Li _1.10Ni_0.72Co_0.16
Nb_0.02O_1.85F_0.15, LiNi_1-xyCo_xM_yO₂(However
However, the M is at least selected from Al, B and Nb.
One element, x and y are 0 <x ≦ 0.5, 0 <y <
0.5 and 0 <x + y ≦ 0.5)
Examples thereof include titanium nickel composite oxide.

Among them, the composition formula LiNi_1-xyCo_xM_yO₂
(However, M is a small amount selected from Al, B, and Nb.
Both are one kind of element, and x and y are 0 <x ≦ 0.5 and 0 <y.
<0.5 and 0 <x + y ≦ 0.5)
It is preferable to use a lithium nickel composite oxide.
Specifically, LiNi_1-xyCo_xAl_yO₂, LiNi_1-
xyCo_xB_yO₂, LiNi_1-xyCo_xNb_yO₂, LiN
i_1-abcCo_aAl_bNb _cO₂Can be mentioned
It (Where x and y are 0 <x ≦ 0.5, 0 <y <0.5,
And 0 <x + y ≦ 0.5, where a, b, and c are 0 <a ≦
0.5, 0 <b <0.5, 0 <c <0.5, and 0 <a
+ B + c ≦ 0.5) Such lithium nickel
Complex metal oxides have high thermal stability and excellent safety
preferable.

Specific examples of the spinel type lithium manganese oxide include Li _{1 + a} Mn _2-a O ₄ and Li _{1 + a} Mn.
_2-ab Co _b O ₄ , Li _{1 + a} Mn _2-ab Al _b O ₄ , Li _{1 + a}
Mn _2-ab Fe _b O ₄ , Li _{1 + a} Mn _2-ab Mg _b O ₄ , L
i _{1 + a} Mn _2-ab Ti _b O ₄ , Li _{1 + a} Mn _2-ab Nb
_{b O 4, Li 1 + a} Mn 2-ab Ge b O 4 and the like. (The a represents 0 <a and 2> a + b) As the conductive agent, for example, acetylene black, carbon black, artificial graphite, natural graphite or the like can be used.

Examples of the binder include polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PV).
dF), modified PVdF in which at least one of hydrogen or fluorine of PVdF is substituted with another substituent, a copolymer of vinylidene fluoride-6-fluorinated propylene, polyvinylidene fluoride-tetrafluoroethylene-6-fluorinated propylene. Can be used.

As the organic solvent for dispersing the binder, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF) and the like are used.

The current collector has, for example, a thickness of 10 to 25 μm.
m aluminum foil, stainless steel foil, titanium foil and the like.

The thickness of one side of the positive electrode active material layer is 30 to 10
It is preferably 0 μm. When the thickness is in this range, the large current discharge characteristics are improved. The preferable range of this thickness is 50 μm to 65 μm.

In the positive electrode 7, the packing density of the active material layer after rolling is preferably 2.7 g / cm ³ or more. More preferably, it is 3.0 g / cm ³ or more. Packing density of 3.0 g / cm ³
With the above, the capacity of the battery can be increased. However, if the packing density is too high, the large-current discharge characteristics may deteriorate, so the upper limit of the packing density is preferably 3.5 g / cm ³ or less. c) Negative Electrode 9 The negative electrode 9 is made of, for example, a carbonaceous material that occludes / releases lithium ions or a material containing a chalcogen compound, a light metal, or the like. Of these, a negative electrode containing a carbonaceous material or a chalcogen compound that occludes / releases lithium ions is preferable because the battery characteristics such as the cycle life of the secondary battery are improved.

Examples of the carbonaceous material that absorbs and releases lithium ions include coke, carbon fiber, pyrolytic vapor-phase carbonaceous material, graphite, resin fired body, mesophase pitch carbon fiber or mesophase spherical carbon fired body. You can Above all, it is preferable to use mesophase pitch carbon fiber or mesophase spherical carbon graphitized at 2500 ° C. or higher because the electrode capacity increases.

Examples of chalcogen compounds that absorb and release lithium ions include titanium disulfide (TiS ₂ ), molybdenum disulfide (MoS ₂ ), and niobium selenide (NbSe ₂ ).
And so on. When such a chalcogen compound is used for the negative electrode, the voltage of the secondary battery drops, but the capacity of the negative electrode increases, so that the capacity of the secondary battery is improved. Further, since the negative electrode has a high diffusion rate of lithium ions, the rapid charge / discharge performance of the secondary battery is improved.

Examples of the light metal include aluminum, aluminum alloy, magnesium alloy, lithium metal, lithium alloy and the like.

For the negative electrode (for example, a negative electrode made of a carbon material), specifically, a negative electrode material paste obtained by dispersing a carbon material, a conductive agent and a binder in an appropriate solvent is applied to a current collector on one side or both sides. It is prepared by coating.

Examples of the binder include polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PV).
dF), ethylene-propylene-diene copolymer (EP
DM), styrene-butadiene rubber (SBR) and the like can be used.

As the current collector, for example, copper foil, nickel foil or the like can be used, but copper foil is most preferable in consideration of electrochemical stability and flexibility during winding. At this time, the thickness of the foil is 8 μm or more and 15 μm
The following is preferable.

The thickness of one surface of the negative electrode active material layer is 30 to 10
It is preferably 0 μm. When the thickness is in this range, the large current discharge characteristics are improved. The preferable range of the thickness is 50 μm to 65 μm.

In the negative electrode 9, the packing density of the active material layer after rolling is preferably 1.35 g / cm ³ or more. More preferably, it is 1.4 g / cm ³ or more. Packing density 1.4g /
If it is cm ³ or more, the capacity of the battery can be increased. However, if the packing density is too high, the high-current discharge characteristics may deteriorate, so the upper limit of the packing density is preferably 1.5 g / cm ³ or less. d) Electrolytic solution The electrolytic solution has a composition in which an electrolyte is dissolved in a non-aqueous solvent.

Examples of the non-aqueous solvent include cyclic carbonates such as propylene carbonate (PC) and ethylene carbonate (EC), such as dimethyl carbonate (D).
Chain carbonate such as MC), methyl ethyl carbonate (MEC), diethyl carbonate (DEC),
Chain ethers such as 1,2-dimethoxyethane (DME) and diethoxyethane (DEE), tetrahydrofuran (THF) and 2-methyltetrahydrofuran (2-Me
THF) and other cyclic ethers and crown ethers, γ-
At least one selected from fatty acid esters such as butyrolactone (γ-BL), nitrogen compounds such as acetonitrile (AN), and sulfur compounds such as sulfolane (SL) and dimethyl sulfoxide (DMSO) can be used.

Among them, at least one selected from EC, PC and γ-BL, EC, PC and γ-B
At least one selected from L and DMC, MEC, DE
It is desirable to use a mixed solvent containing at least one selected from C, DME, DEE, THF, 2-MeTHF, and AN. Further, when a negative electrode containing a carbonaceous material that absorbs and releases the lithium ions is used, from the viewpoint of improving the cycle life of the secondary battery including the negative electrode, EC and PC and γ-BL, EC and PC And MEC, E
C and PC and DEC, EC and PC and DEE, EC and AN,
EC and MEC, PC and DMC, PC and DEC, or E
It is desirable to use a mixed solvent of C and DEC.

Examples of the electrolyte include lithium perchlorate (LiClO ₄ ) and lithium hexafluorophosphate (LiP).
F ₆ ), lithium borofluoride (LiBF ₄ ), lithium hexafluoroarsenide (LiAsF ₆ ), lithium trifluorometasulfonate (LiCF ₃ SO ₃ ), lithium aluminum tetrachloride (LiAlCl ₄ ), bistrifluoromethylsulfonylimide lithium [LiN (CF ₃ SO ₂ ) ₂ ]
Examples thereof include lithium salts. Above all, LiP
If F ₆ , LiBF ₄ , and LiN (CF ₃ SO ₂ ) ₂ are used,
It is preferable because conductivity and safety are improved.

The amount of the electrolyte dissolved in the non-aqueous solvent is
It is preferably in the range of 0.5 mol / L to 2.0 mol / L.

As described in detail above, in the above-mentioned non-aqueous electrolyte secondary battery, the spacer in which the plurality of groove-shaped irregularities are formed in the direction along the height direction of the spiral electrode group is the spiral electrode. Since it is located at the outermost periphery of the group, even if gas pressure is generated inside the electrode group due to abnormalities and the electrode group expands in the diametrical direction, the flow of gas between the electrode group and the battery container is caused by the groove-shaped irregularities. The road is secured. The generated gas moves toward the safety valve arranged above the electrode group through this flow path, and is rapidly released to the outside through the safety valve, so that it does not stay in the battery container. Therefore, the deformation of the battery container and the rupture of the battery can be prevented in advance.

Further, if the spacer having the concavo-convex portion is used as an adhesive tape for fixing the winding end portion of the spiral electrode group, the number of parts loaded does not increase and there is no need to change the manufacturing process. Therefore, it is possible to secure battery safety while suppressing cost increase. (Embodiment of the Second Invention) A difference from the embodiment of the first invention is a spacer. This spacer is a processed product formed by bending a metal plate to form the groove-shaped uneven portion. Since the other points are the same as those of the first embodiment, a description will be added below regarding this spacer.

FIG. 4 is a sectional view in the circumferential direction showing a gear-shaped metal plate 17 which is an example of the above-mentioned processed product which is this spacer and which is fixed to the outermost periphery of the spiral electrode group 4. . With such a configuration, when gas pressure is generated inside the spiral electrode group 4 and the spiral electrode group 4 expands in the diametrical direction at the time of abnormality, the spiral electrode group 4 and the spiral electrode group 4 are formed by the irregularities on the surface of the spacer 17. A gas flow path is secured between the battery containers 5, and at the same time, the gear-like metal plate 17 comes into contact with the battery container 5 to generate heat such as Joule heat generated from the spiral electrode group 4 into the spiral electrode group 4. From the gear-shaped metal plate 1
In order to transfer heat to the battery container 5 via 7, the spiral electrode group 4
It is possible to prevent the abnormal heat storage of, and it is possible to obtain an effect that higher safety can be secured.

Examples of the material of the gear-shaped metal plate 17 include copper, nickel, nickel-plated copper and nickel-plated iron.

Further, when a gear-shaped metal plate made of metal is used as the spacer, when gas pressure is generated inside the electrode group and the electrode group expands in the diametrical direction at the time of abnormality, the electrode group is formed by the groove-shaped uneven portion. At the same time that a gas flow path is secured between the battery group and the battery case, heat such as Joule heat generated from the electrode group when the gear-shaped metal plate comes into contact with the battery case is removed from the electrode group by the gear-shaped metal plate. Since heat is transferred to the battery container via the battery, it is possible to prevent abnormal heat storage in the electrode group, and to ensure higher safety.

[0057]

EXAMPLES Examples of the present invention will be specifically described below. The following examples employ the battery structure described in the embodiment of the first invention. (Example 1) First, a positive electrode and a negative electrode were produced as follows <Production of positive electrode> Polyvinylidene fluoride was N-methyl-2.
LiCoO ₂ powder, acetylene black and graphite as a conductive agent are added to a solution dissolved in pyrrolidone, and the mixture is stirred and mixed, and 90% by weight of LiCoO ₂ , 3% by weight of acetylene black, 3% by weight of graphite, and 4% of polyvinylidene fluoride. A positive electrode mixture consisting of wt% was prepared. This positive electrode mixture was applied to both sides of an aluminum foil (thickness 20 μm), dried, and then pressure-molded using a roller press machine to produce a belt-shaped positive electrode having a thickness of 140 μm. <Fabrication of Negative Electrode> Mesophase pitch carbon fiber made of mesophase pitch as a raw material was heated to 1000 ° C. under an argon atmosphere.
After carbonization with an average fiber length of 30 μm and an average fiber diameter of 11
μm, particle size 1 to 80 μm, and 90% by volume, and appropriately pulverize particles having a particle size of 0.5 μm or less (5% or less), and then graphite at 3000 ° C. in an argon atmosphere. To produce a carbonaceous material.

Polyvinylidene fluoride was added to N-methyl-2-
The above-mentioned carbonaceous material and artificial graphite are added to a solution dissolved in pyrrolidone and mixed with stirring to prepare a negative electrode mixture having a mixture composition of 86% by weight carbonaceous material, 10% by weight artificial graphite, and 4% by weight polyvinylidene fluoride. did. Copper foil (thickness 12
(μm) on both sides, dried and then pressure-molded with a roller press to prepare a negative electrode. At this time, the packing density and the electrode length were adjusted so that the ratio (capacity balance) of the design capacity of the negative electrode to the design capacity of the positive electrode after molding was 1.05 or more and 1.1 or less.

A spacer was used in which the support was made of polyester, the adhesive material was made of an acrylic adhesive, and the groove-like uneven portions having the shape as shown in FIG. 1 were formed. The spacer has a total thickness of 250 μm including the adhesive layer,
The depth of the groove-shaped recess is 200 μm. The width of this spacer, that is, the length in the direction along the height direction of the spiral electrode group is 60 mm. The ratio L ₁ / L ₂ of the length in the height direction of the spiral electrode group to the height of the spiral electrode group is 0.99.
Is. The thickness of the adhesive material layer is 25 μm.

After welding a positive electrode lead made of aluminum and a negative electrode lead made of nickel to the positive electrode and the negative electrode, respectively, the positive electrode, a separator made of a microporous polyethylene film having a thickness of 25 μm, and the negative electrode are respectively arranged in this order. An electrode group was produced by stacking and spirally winding the negative electrode so that the negative electrode was located outside. The sheet on which the groove-shaped uneven portion is formed is used as an adhesive tape for fixing the outermost winding end portion of the spiral electrode group, and the groove is formed as shown in FIG. -Shaped recesses were arranged without gaps so as to face the battery container side and wrap around the center of the outermost periphery of the spiral electrode group in the height direction and the outermost periphery of the electrode group. <Assembly of Battery> The electrode group configured as described above was housed in a battery container made of nickel-plated iron, the negative electrode lead was placed at the bottom of the battery container, and the positive electrode lead was placed at the opening of the battery container. Welded to each safety valve with current cutoff function.

Subsequently, ethylene carbonate (EC) and methyl ethyl carbonate (MEC) were placed in the battery container.
The non-aqueous electrolytic solution prepared by dissolving 1 M of lithium hexafluorophosphate (LiPF ₆ ) in the mixed solvent (mixing volume ratio 1: 2) was injected to sufficiently impregnate the electrode group with the non-aqueous electrolytic solution. Then, after disposing the positive electrode terminal on the safety valve and caulking and fixing it, a cylindrical lithium ion secondary battery (18650 size) having a design rated capacity of 1600 mAh was assembled. (Example 2) A spacer having groove-shaped uneven portions having the same material and shape as in Example 1 was used, except that the width of the spacer was 48 mm. Ratio L ₁ of the length in the direction along the height direction of the spiral electrode group and the height of the spiral electrode group
/ L ₂ is 0.8. Hereinafter, in the same manner as in Example 1,
The spacer having the groove-shaped concavo-convex portion was arranged on the outermost periphery of the spiral electrode group. (Example 3) A spacer having groove-shaped concavo-convex portions having the same material and shape as in Example 1 was used except that the width of the spacer was 40 mm. Ratio L ₁ of the length in the direction along the height direction of the spiral electrode group and the height of the spiral electrode group
/ L ₂ is 0.67. Thereafter, in the same manner as in Example 1, the sheet on which the groove-shaped uneven portion was formed was arranged on the outermost periphery of the spiral electrode group. (Example 4) A sheet having groove-shaped uneven portions having the same material and shape as in Example 1 was used, except that the width of the spacer was 30 mm. Ratio of the length in the direction along the height direction of the spiral electrode group to the height of the spiral electrode group L ₁ /
L ₂ is 0.5. Hereinafter, in the same manner as in Example 1, the spacer having the groove-shaped concavo-convex portion was arranged on the outermost periphery of the spiral electrode group. (Example 5) A spacer having groove-shaped concavo-convex portions having the same material and shape as in Example 1 was used except that the width of the spacer was 20 mm. Ratio L ₁ of the length in the direction along the height direction of the spiral electrode group and the height of the spiral electrode group
/ L ₂ is 0.33. Hereinafter, in the same manner as in Example 1, the spacer having the groove-shaped irregularities was arranged on the outermost periphery of the spiral electrode group. (Embodiment 6) A spacer having groove-like concavo-convex portions having the same material and shape as in Embodiment 5 was used, and the spacer was arranged at the outermost periphery of the spiral electrode group. At this time, the spiral electrode group was arranged so that the lower end of the spiral electrode group and the lower end of the spacer were aligned with each other. (Embodiment 7) A spacer having groove-like concavo-convex portions having the same material and shape as in Embodiment 5 was used, and the spacer was arranged at the outermost periphery of the spiral electrode group. At this time, the upper end of the spiral electrode group and the upper end of the spacer were aligned with each other. (Embodiment 8) A spacer having the same material and shape as in Embodiment 2 and provided with groove-shaped concavo-convex portions was used as an adhesive tape for fixing the outermost winding end portion of the spiral electrode group. BEST MODE FOR CARRYING OUT THE INVENTION Embodiment of the invention: As shown in FIG. 2 (a), the spiral-shaped electrode group has a center in the height direction of the outermost periphery and an outermost periphery of the electrode group so that the groove-shaped recess faces the battery container side. Was arranged so as to cover 50% in the circumferential direction. (Embodiment 9) A spacer having the same material and shape as in Embodiment 2 and having groove-shaped concavo-convex portions was used as an adhesive tape for fixing the outermost winding end portion of the spiral electrode group. BEST MODE FOR CARRYING OUT THE INVENTION Embodiment of the invention: As shown in FIG. 2 (a), the spiral-shaped electrode group has a center in the height direction of the outermost periphery and an outermost periphery of the electrode group so that the groove-shaped recess faces the battery container side. Was arranged so as to cover 75% in the circumferential direction. (Example 10) A spacer having the same material and shape as in Example 2 and having groove-shaped concavo-convex portions was used as an adhesive tape for fixing the outermost winding end portion of the spiral electrode group.
As shown in FIG. 2 (b), an embodiment of the present invention is configured such that the groove-shaped concave portion faces the electrode group side and the center of the outermost periphery of the spiral electrode group in the height direction and the electrode. It was arranged without any gap so as to wrap the outermost periphery of the group. (Example 11) The support was made of polyimide, and Example 2 was used.
A spacer having a groove-shaped concavo-convex portion having the same shape as was used. Hereinafter, in the same manner as in Example 1, the spacer having the groove-shaped uneven portion was arranged on the outermost periphery of the spiral electrode group. (Example 12) The support is polyester, the adhesive material is an acrylic adhesive, and the total thickness including the adhesive layer is 200.
A spacer having a groove-shaped concave and convex portion with a groove-shaped concave portion having a depth of 150 μm was used. The width of this spacer,
The thickness of the adhesive material layer is the same as in Example 2.

Next, the winding end portion of the outermost periphery of the produced spiral electrode group was adhered to a polyester adhesive tape (thickness: 50 μm).
It fixed by m). Then, on the spacer on which the groove-shaped concave and convex portions are formed, the groove-shaped concave portion faces the battery container side, and the center of the outermost circumference of the spiral electrode group in the height direction and the electrode group. Arrange without gaps so as to wrap the outermost circumference,
It was fixed with an adhesive material applied to one surface of the spacer having the groove-shaped uneven portion. (Embodiment 13) A gear-shaped metal plate made of copper and having a plate thickness of 20 μm and a groove-shaped recess having a depth of 200 μm is used as a spacer having a groove-shaped uneven portion. did. The space (pitch) between the recesses of the gear-shaped metal plate is 1.5 mm, the width is 50 mm, and the length in the direction along the height direction of the spiral electrode group and the height of the spiral electrode group are equal to each other. The ratio L ₁ / L ₂ is 0.83. Hereinafter, in the same manner as in Example 1, the gear-shaped metal plate was arranged on the outermost periphery of the spiral electrode group. (Example 14) A gear-shaped metal plate having the same shape as that of Example 13 except that the material was nickel was used. This gear-shaped metal plate was arranged on the outermost periphery of the spiral electrode group. Hereinafter, in the same manner as in Example 1, the gear-shaped metal plate was arranged on the outermost periphery of the spiral electrode group. (Comparative Example 1) In the same spiral electrode group as that produced in Example 1, the outermost winding end portion was fixed with a polyester adhesive tape (thickness 50 µm). The adhesive tape is not provided with groove-shaped irregularities. Nothing was placed on the outermost periphery of the spiral electrode group. (Comparative Example 2) Sheets made of EPDM rubber and having a thickness of 200 µm and a width of 7.5 mm were arranged as spacers on both ends of the outermost periphery of the same spirally wound electrode group as that manufactured in Example 1. The spacer is divided into two pieces, and a gap is formed without contacting each other. The sum of the lengths of the spacers in the circumferential direction of the electrode group was 80% of the circumferential length. <Battery Safety Evaluation-Crush Test> Each of the batteries of Examples 1 to 14 and Comparative Examples 1 and 2 obtained as described above was first subjected to a capacity confirmation test. The capacity confirmation test shows that the charging current is 480 mA at 20 ° C.
After the voltage has reached 4.2V, the voltage is kept at a constant voltage of 4.2V.
It went for a total of 8 hours. Discharge is performed with a constant current of 320 mA,
The final discharge voltage was 2.7V. The rest time after charging and discharging was 30 minutes each. The obtained discharge capacity was measured as the discharge capacity of the battery and is shown in Table 1. As shown in Table 1, Examples 1 to 13 and Comparative Examples 1 to 2
All of the batteries are rated design capacity (1600mA
It was confirmed that the values shown in h) were obtained.

Next, a predetermined number of batteries of Examples 1 to 14 and Comparative Examples 1 to 2 were prepared, and the above charging / discharging was repeated 5 times, followed by charging to 4.2V charging state. A central part crush test was carried out in which the central part of each battery was crushed with a round bar until the diameter of the battery became 1/2 of the initial size.
The results are shown in Table 1. As an evaluation rank, 100 test samples were prepared for each of the examples, and the result of the central part crushing test was expressed as a ratio to 100 batteries in which no abnormality such as rupture or ignition was observed, and the AA rank was 100% to 100%.
98% or more, A rank is less than 98%, 90% or more, B rank is less than 90%, 80% or more, and C rank is less than 80%.

[0064]

[Table 1]

As is clear from Table 1, the batteries of Examples 1 to 14 provided with the spacers having the groove-shaped irregularities according to the present invention were rated as the safety valves because the safety valves worked reliably. It was confirmed that it was as safe as A or higher. Particularly, the ratio L ₁ / L ₂ of the length in the direction along the height direction of the spiral electrode group and the height of the spiral electrode group is 0.67 or more. Examples 1 to 3 and Examples 9 to 9 No. 14 had no batteries that ruptured or ignited.

On the other hand, in the battery of Comparative Example 1, many batteries that ruptured or ignited were found, and the evaluation rank was C rank. The evaluation rank of the battery of Comparative Example 2 was B rank.

Next, Examples 1 to 14 and Comparative Example 1
-For each battery of Comparative Example 2, a can bottom crushing test was carried out in which the can bottom portion of each battery in a 4.2V charged state was crushed. The other test conditions and evaluation ranks are exactly the same as the central part crush test. The results are shown in Table 2.

[0068]

[Table 2]

As is clear from Table 2, in the batteries of Examples 1 to 14 provided with the spacers having the groove-shaped irregularities according to the present invention, in the can bottom crushing test harsher than the central part crushing test. Moreover, it was confirmed that all the evaluation ranks were A rank or higher, indicating high safety. In particular, in Example 2, Example 3, and Example 8 to Example 14, it was confirmed that the evaluation rank shows AA rank, which is very high safety.

The evaluation rank of the other examples was A rank. From this, it is important that the spacer with the groove-shaped irregularities that become gas passages in the event of an abnormality be placed at the center of the outermost circumference of the spirally wound electrode group in the height direction. I understand.

On the other hand, in the battery of Comparative Example 1, as in the result of the central portion crushing test, many batteries were found to have ruptured or ignited, and the evaluation rank was C rank.

The battery of Comparative Example 2 was ranked B in the results of the central part crushing test, but in the can bottom crushing test, many batteries were found to have ruptured or ignited, and the evaluation rank was ranked C. It was <Battery Safety Evaluation-Overcharge Test> Next, assuming a charger failure, each battery of Examples 1 to 14 and Comparative Examples 1 to 2 was fully charged at 4.2V. , Further, each is rapidly charged at a current value of 8A (5C), and 15V
After the temperature reached, an overcharge test was performed in which charging was performed at a constant voltage. The results are shown in Table 3. As an evaluation rank, 100 test samples were prepared in each of the examples, and the result of the overcharge test was expressed as a ratio with respect to 100 batteries in which no abnormality such as deformation or rupture of the battery container was observed. A rank is 1
00% to 98% or more, B rank is less than 98%, 80% or more, and C rank is less than 80%.

[0073]

[Table 3]

As is clear from Table 3, in the batteries of Examples 1 to 14, since the safety valves were activated and the leaflets were cleaved and the current was cut off normally, the evaluation ranks were all A ranks or higher. It was confirmed that it showed high safety.
In particular, in Examples 13 and 14 in which the gear-shaped metal plate was used as the sheet having the groove-shaped concavo-convex portion, there were no batteries that ruptured or ignited.

On the other hand, in the batteries of Comparative Examples 1 and 2, many abnormalities such as deformation, rupture and ignition of the battery container were observed.

Next, the same positive electrode and negative electrode as those used in Example 1 but having different electrode lengths were produced. Two positive electrode leads made of aluminum and two negative electrode leads made of nickel were welded to the positive electrode and the negative electrode, respectively, and then the positive electrode was formed to a thickness of 2
A separator made of a microporous polyethylene film having a thickness of 5 μm and the negative electrode were laminated in this order, and spirally wound so that the negative electrode was positioned on the outer side to prepare a spiral electrode group.

This was housed in a battery container having a diameter of 26 mm and a height of 650 mm, and in the same manner as in Example 1, the designed rated capacity was 3 A.
A cylindrical lithium ion secondary battery of h (26650 size) was assembled. Even in a battery having a different shape from those of the examples, the same sheets as those of the examples 1 to 14 can be obtained by using the same sheet having the groove-shaped concavo-convex portions as those of the examples 1 to 14. The action and effect were obtained.

As described above, since the spacer having the plurality of groove-shaped irregularities formed in the height direction of the spiral electrode group is arranged at the outermost periphery of the spiral electrode group, the electrode is not used when an abnormality occurs. Even if the gas pressure is generated inside the group and the electrode group expands in the diameter direction, the groove-like uneven portion secures a gas flow path between the electrode group and the battery container, and the generated gas passes through this flow path to the electrode. It moves toward the safety valve located at the upper part of the group and is quickly released to the outside through the safety valve, so it does not stay in the battery container and it is possible to prevent deformation of the battery container and rupture of the battery in advance. It is possible to provide a high-power cylindrical water electrolyte secondary battery having excellent properties. Therefore, it is extremely useful as a power source for power tools, uninterruptible power supplies (UPS), cordless cleaners, and the like.

[0079]

According to the above structure, even if the electrode group expands due to gas generation, the generated gas can be led out from the electrode group to prevent the battery container from swelling or rupturing, which is excellent in safety. A non-aqueous electrolyte secondary battery can be provided.

[Brief description of drawings]

FIG. 1 is a development view and a cross-sectional view illustrating a main part according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an electrode group according to the embodiment of the present invention.

FIG. 3 is a perspective view showing an internal structure of the battery according to the embodiment of the present invention.

FIG. 4 is a sectional view of an electrode group according to an embodiment of the present invention.

FIG. 5 is a vertical cross-sectional view of a non-aqueous electrolyte secondary battery according to an embodiment of the present invention.

[Explanation of symbols]

1 ... Sheet (support) on which groove-like irregularities are formed 2 ... Adhesive material 3 ... Groove 4 ... Swirl type electrode group 5: Battery container 6 ... Insulator 7 ... Positive electrode 8: Separator 9 ... Negative electrode 10 ... valve membrane 11 ... Safety valve 12 ... Positive electrode terminal 13 ... Gasket 14 ... Gas vent hole 15 ... Positive electrode lead 16 ... Negative electrode lead 17 ... Gear-shaped metal plate

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yuji Sato             1st Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa             Inside the Toshiba Research and Development Center (72) Inventor Motoko Kanda             1st Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa             Inside the Toshiba Research and Development Center F term (reference) 5H029 AJ12 AK03 AK18 AL04 AL06                       AL07 AL11 AL12 AM03 AM04                       AM05 AM07 BJ02 BJ14 BJ27                       CJ03 CJ05 CJ06 CJ07 DJ04                       EJ01 EJ12 HJ04

Claims (5)

[Claims] 1. A columnar electrode group in which a strip-shaped negative electrode, a separator and a strip-shaped positive electrode are sequentially laminated, a non-aqueous electrolyte solution impregnated in the separator, and a columnar battery container containing the electrode group and the non-aqueous electrolyte solution. A non-aqueous electrolyte secondary battery comprising: a spacer for forming a groove-shaped uneven portion between the electrode group and the battery container and in a direction parallel to the axis of the electrode group; If the length of the spacer parallel to the height direction of the group is L ₁ and the height of the electrode group is L ₂ , the ratio L
₁ / L ₂ is 0.33 or more, a non-aqueous electrolyte secondary batteries, characterized by at 0.99 or less. 2. The non-aqueous electrolyte secondary battery according to claim 1, wherein the ratio L ₁ / L ₂ is 0.83 or less. 3. The non-aqueous electrolyte secondary battery according to claim 1, wherein the spacer has a plurality of rod-shaped constituent members formed on the outer periphery of the electrode group. 4. The non-aqueous electrolyte secondary battery according to claim 1, wherein the spacer is a processed product in which a metal plate is bent to form the groove-shaped uneven portion. 5. The non-aqueous electrolyte secondary battery according to claim 1, wherein the spacer is fixed to the outermost peripheral surface of the electrode group with an adhesive material.