JP2003282034A - Non-aqueous secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-aqueous secondary battery, which is flat-shaped, has the thickness less than 12 mm, and has a large capacity of 30 Wh or more as well as a volume energy density of 180 Wh/l to realize a high weight energy density. <P>SOLUTION: In the non-aqueous secondary battery which houses a positive electrode, a negative electrode, a separator, and non-aqueous electrolyte containing lithium salt in a battery container, and which is flat-shaped, has the thickness less than 12 mm, and has a large energy capacity of 30 Wh or more, and the volume energy density of 180 Wh/l or more, the battery container is provided with a part consisting of aluminum or of an alloy mainly composed of aluminum as the major constituting member. <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 secondary battery, and more particularly to a non-aqueous secondary battery for a power storage system.

[0002]

2. Description of the Related Art In recent years, from the viewpoint of effective use of energy and resource saving for the purpose of resource saving and global environmental problems, a distributed power storage system for home use for electric power storage of late night electric power storage and solar power generation Power storage systems are attracting attention. For example, in Japanese Patent Laid-Open No. 6-86463,
As a system capable of supplying energy to energy consumers under optimum conditions, a total system combining electricity supplied from a power plant, gas cogeneration, a fuel cell, a storage battery, etc. has been proposed. The secondary battery used in such a power storage system has an energy capacity of 10
Unlike a small secondary battery for mobile devices of Wh or less, a large one having a large capacity is required. Therefore, in the above-described power storage system, a plurality of secondary batteries are usually stacked in series and used as an assembled battery having a voltage of, for example, 50 to 400 V. In most cases, lead batteries have been used.

On the other hand, in the field of small secondary batteries for portable equipment, nickel hydrogen batteries and lithium secondary batteries have been developed as new type batteries to meet the needs of small size and high capacity, and volume energy of 180 Wh / l or more has been developed. Batteries having a density are commercially available. Especially, the lithium-ion battery
Since it has a volume energy density of more than 350 Wh / l, and is superior in reliability such as safety and cycle characteristics to a lithium secondary battery using metallic lithium as a negative electrode, its market is dramatically increased. It has been postponed.

In response to this, even in the field of large batteries for power storage systems, lithium ion batteries are targeted as a candidate for high energy density batteries, and vigorous development is underway at the lithium battery power storage technology research association (LIBES) and the like. Has been.

The energy capacity of these large-sized lithium ion batteries is about 100 Wh to 400 Wh, and the volume energy density is 200 to 300 Wh / l, which is about the same level as small secondary batteries for portable devices. Its shape is
Diameter 50mm-70mm, Length 250mm-450mm
The cylindrical type, the flat type having a thickness of 35 mm to 50 mm, the oblong rectangular type, or the like having a thickness of 35 mm to 50 mm is typical.

However, although such a large lithium-ion battery can obtain a high energy density, its battery design is generally on the extension line of a small battery for portable devices, so that the diameter or thickness for portable devices is large. The battery has a cylindrical shape, a rectangular shape, or the like that is three times or more that of a small battery. In this case, heat is likely to be accumulated inside the battery due to Joule heat generation due to internal resistance of the battery during charging / discharging, or internal heat generation of the battery due to change in entropy of the active material due to entry and exit of lithium ions. For this reason, there is a large difference between the temperature inside the battery and the temperature near the surface of the battery, and the internal resistance is unevenly distributed along with this, and as a result, variations in the charge amount and voltage are likely to occur.
Further, since a plurality of batteries of this type are used as an assembled battery, the easiness of heat storage also varies depending on the installation position of the batteries in the system, and variations among the batteries occur, thus ensuring accurate control of the entire assembled battery. It will be difficult. Furthermore, since the heat dissipation is insufficient during high-rate charging / discharging, etc., the battery temperature rises and the battery is placed in an unfavorable state, which shortens the service life due to decomposition of the electrolyte, and also causes thermal runaway of the battery. However, there was a problem with reliability, especially safety.

In order to solve the above problems, WO99 / 60
No. 652 is a flat non-aqueous secondary battery in which a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte containing a lithium salt are housed in a battery container, and the non-aqueous secondary battery has a thickness Discloses a non-aqueous secondary battery having a flat shape of less than 12 mm, an energy capacity of 30 Wh or more and a volume energy density of 180 Wh / l or more. It is proposed that the battery has a unique battery shape (flat shape) to solve the problems of reliability and safety due to the heat storage, which is a barrier to practical use.

By the way, generally, a battery container has a function of withstanding an external impact such as a collision of an object, and holding an electrode housed in the battery container to hold down an electrode when gas is generated. In addition, the material, shape, and the like are selected according to the battery size, the battery shape, the environment in which the battery is used, and the like. Especially for a large battery, unlike a small battery, in order to secure the reliability and safety of the battery, the design of the battery container, that is, the determination of the material, the shape, etc., is particularly important. For example, when the battery shape is rectangular, a high-strength material is required because the flat plate portion has lower pressure resistance than a cylindrical battery, so stainless steel or iron is generally used as the material of the battery container. Has been.

However, the thickness as described above is 12 m.
In a large flat battery having a large capacity (30 Wh or more) of less than m, a flat plate-shaped member having a large area exists, and the ratio of the volume of the battery container material to the entire battery is larger than that of the prismatic or cylindrical battery. Therefore, in such a thin and flat battery, when stainless steel or iron is used for the battery container, there is a problem that the ratio of the weight of the battery container to the total battery weight is high. That is, the conventional flat-shaped battery has a problem that the weight energy density is extremely lowered although the high volume energy density can be realized.

Therefore, if an aluminum-based material is used for the battery container, the container weight can be reduced to about one-third, and the decrease in the weight energy density can be suppressed. However, when high-purity aluminum is used for both the bottom container and the upper lid, there are problems that the laser weldability is deteriorated and the aluminum is easily deformed by external stress. Further, when an aluminum alloy having a high laser weldability is used for both the bottom container and the top lid, the material hardness becomes high, it becomes difficult to draw with a small R (radius of curvature), and it is difficult to increase the internal effective volume of the entire battery. There was a problem.

[0011]

An object of the present invention is to provide a non-aqueous secondary battery having a flat shape with a thickness of less than 12 mm and having a high capacity, a high volume energy density and a high weight energy density. To provide a secondary battery.

[0012]

To achieve the above object, the present invention provides the following non-aqueous secondary battery.

Item 1. A positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte containing a lithium salt are housed in a battery container and have a flat shape with a thickness of less than 12 mm, and the energy capacity thereof is 30 Wh or more and the volume energy density is 180 Wh /
In the non-aqueous secondary battery of 1 or more, the battery container is composed of a flat plate-shaped upper lid and a drawn bottom container, and the upper lid is provided with a portion made of an aluminum alloy as a main member, and the bottom container is A non-aqueous secondary battery, which is provided with a portion made of high-purity aluminum metal as a main member.

Item 2. The bottom container in the battery container is 9
Item 2. The non-aqueous secondary battery according to item 1, which is composed of high-purity aluminum containing 9% by weight or more of an Al component.

Item 3. The upper lid of the battery container is 0.
Item 3. The non-aqueous secondary battery according to item 2, which is composed of an aluminum alloy containing 5 wt% to 2.0 wt% of Mn component.

Item 4. The upper lid of the battery container is 0.
The non-aqueous secondary battery according to claim 3, which is composed of an aluminum alloy containing 02 wt% to 0.8 wt% Mg component.

Item 5. Item 5. The non-aqueous secondary battery according to any one of Items 1 to 4, wherein the pressure inside the battery container is less than atmospheric pressure.

Item 6. Item 6. The non-aqueous secondary battery according to item 5, wherein the pressure inside the battery container is kept below atmospheric pressure by finally sealing after the pressure inside the battery container is kept below atmospheric pressure after being charged at least once. Next battery.

Item 7. The pressure in the battery container is 8.66.
Item 7. The non-aqueous secondary battery according to any one of Items 1 to 6, which has a pressure of 10 ⁴ Pa or less.

Item 8. Item 8. The non-aqueous secondary battery according to any one of Items 1 to 7, wherein the negative electrode contains a substance capable of doping and dedoping lithium.

Item 9. Item 9. The non-aqueous secondary battery according to any one of Items 1 to 8, wherein the positive electrode contains manganese oxide.

Item 10. Item 10. The non-aqueous secondary battery according to any one of Items 1 to 9, wherein the front and back surfaces of the flat shape are rectangular.

Item 11. The thickness of the battery container is 0.2 mm
Item 11. The non-aqueous secondary battery according to any one of Items 1 to 10, which is 1 mm or less.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION A non-aqueous secondary battery according to an embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a plan view and a side view of a flat rectangular (notebook type) non-aqueous secondary battery for an electricity storage system, which is an example of the present embodiment, and FIG. 2 is an internal view of the battery shown in FIG. 1. It is a side view which shows the electrode laminated body accommodated in.

As shown in FIGS. 1 and 2, the non-aqueous secondary battery according to the present embodiment has a battery container including an upper lid 1 and a bottom container 2, and a plurality of positive electrodes contained in the battery container. 101a, negative electrodes 101b and 101c, and separator 1
And an electrode laminated body of No. 04. In the case of the flat non-aqueous secondary battery as in the present embodiment, the positive electrode 101a and the negative electrode 101b (or the negative electrode 10 arranged on both outer sides of the laminate).
1c) is, for example, as shown in FIG.
4 are alternately arranged and laminated, but the present invention is
The arrangement is not particularly limited, and the number of layers and the like can be variously changed according to the required capacity and the like. The shape of the non-aqueous secondary battery shown in FIG. 1 and FIG.
mm × width 210 mm × thickness 6 mm, positive electrode 101a
In the case of a lithium secondary battery in which LiMn ₂ O ₄ is used for the negative electrode and a carbon material is used for the negative electrodes 101b and 101c, the lithium secondary battery can be used, for example, in a power storage system.

Further, as shown in FIG. 1, a positive electrode terminal 3 and a negative electrode terminal 4 are attached to the upper lid 1 of the battery container in a state of being insulated from the upper lid 1, and each of the positive electrode terminals 3 shown in FIG. The positive electrode current collector 105a of the positive electrode 101a is electrically connected, and each of the negative electrodes 101b and 101c is connected to the negative electrode terminal 4.
The negative electrode current collector 105b is electrically connected.

The upper lid 1 and the bottom container 2 form a battery container by melting point A shown in the enlarged view of FIG. 1, that is, the peripheral portion of the upper lid 1 and welding it to the bottom container 2. Examples of the welding method include laser welding, arc welding,
Resistance welding etc. are mentioned. Among them, laser welding is preferable because the welding area is small and energy can be concentrated, so that deformation distortion of the container and thermal influence on the surroundings are small. Top lid 1
The liquid electrolyte injection port 5 is opened, and after the electrolyte is injected, a sealing film 6 made of, for example, an aluminum-modified polypropylene laminate film is used for sealing.

The positive electrode active material used for the positive electrode 101a is not particularly limited as long as it is a lithium-based positive electrode material, and lithium composite cobalt oxide, lithium composite nickel oxide, lithium composite manganese oxide, or a mixture thereof. Further, a system in which one or more different metal elements are added to these composite oxides can be used, and a high-voltage, high-capacity battery can be obtained, which is preferable. In addition, in the case of placing importance on safety, which is the most important issue in the practical application of a large-sized lithium secondary battery, it is preferable to use a positive electrode mainly composed of manganese oxide having a high thermal decomposition temperature. As the manganese oxide, a lithium composite manganese oxide typified by LiMn ₂ O ₄ , a system in which one or more kinds of different metal elements are added to these composite oxides, and Li in which the amount of lithium is more than the stoichiometric ratio are used. _{1 + x} Mn _2-y O ₄ may be mentioned.

The negative electrode active material used for the negative electrodes 101b and 101c is not particularly limited as long as it is a lithium-based negative electrode material, and it is a material capable of doping and dedoping lithium, such as safety and cycle life. This is preferable because it improves reliability. As a material capable of doping and dedoping lithium, a graphite-based material, a carbon-based material, a tin oxide-based material used as a negative electrode material of a known lithium-ion battery,
Examples thereof include metal oxides such as silicon oxides, and conductive polymers represented by polyacene organic semiconductors. In particular, from the viewpoint of safety, a polyacene-based substance that generates little heat at around 150 ° C. and a material containing the same are preferable.

The structure of the separator 104 is not particularly limited, but a single-layer or multi-layer separator can be used, and it is preferable to use at least one non-woven fabric. In this case, cycle characteristics are improved. . The material of the separator 104 is not particularly limited, and examples thereof include polyolefins such as polyethylene and polypropylene, polyamide, kraft paper, glass, and cellulosic materials, and the like, depending on the heat resistance and safety design of the battery. It is decided as appropriate. Among these, polyethylene, polypropylene and the like are preferable from the viewpoint of cost, water content and the like. In the case of using polyethylene or polypropylene as the separator 104, basis weight of the separator is preferably about 5 to 30 g / m ^2, more preferably about 5 to 20 g / m ^2, more preferably 5 to 20 g / m ²
It is a degree. If the basis weight of the separator exceeds 30 g / m ² , the separator becomes too thick, the porosity decreases, and the internal resistance of the battery increases, which is not preferable. On the other hand, when the weight per unit area of the separator is less than 5 g / m ² , practical strength cannot be obtained, which is also not preferable.

As the electrolyte of the secondary battery of the present invention, a known non-aqueous electrolyte containing a lithium salt can be used, which is appropriately determined depending on the use conditions such as the positive electrode material, the negative electrode material and the charging voltage. Is LiPF ₆ , LiBF ₄ ,
A lithium salt such as LiClO _{4 is} added to an organic solvent such as propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, dimethoxyethane, γ-butyrolactone, methyl acetate, methyl formate, or a mixed solvent of two or more of these. Examples include dissolved substances. The concentration of the electrolytic solution is not particularly limited, but is generally 0.5 mol.
/ L to 2 mol / l is practical, and as a matter of course, it is preferable to use an electrolyte having a water content of 100 ppm or less. The non-aqueous electrolyte used in the present specification means a concept including a non-aqueous electrolyte solution and an organic electrolyte solution, and also a concept including a gel or solid electrolyte.

The non-aqueous secondary battery configured as described above can be used in a power storage system for home (night power storage, cogeneration, solar power generation, etc.), a power storage system for electric vehicles, etc. It can have a capacity and a high energy density. In this case, the energy capacity is preferably 30 Wh or more, more preferably 50 Wh or more, and the energy density is preferably 180 Wh /
1 or more, more preferably 200 Wh / l. When the energy capacity is less than 30 Wh or the volume energy density is less than 180 Wh / l, the capacity is small for use in a power storage system, and it is necessary to increase the number of series-parallel batteries to obtain a sufficient system capacity. In addition, it is difficult to make a compact design, which is not preferable for a power storage system.

The non-aqueous secondary battery of this embodiment has a flat shape, and its thickness is less than 12 mm, more preferably less than 10 mm. The lower limit of the thickness is practically 2 mm or more in consideration of the filling rate of the electrodes and the battery size (the smaller the area, the larger the area for obtaining the same capacity). When the thickness of the battery is 12 mm or more, it becomes difficult to sufficiently dissipate the heat generated inside the battery to the outside, or the temperature difference between the inside of the battery and the surface of the battery becomes large,
As a result of the different internal resistances, variations in the amount of charge and voltage in the battery become large. The specific thickness is the battery capacity,
The thickness is appropriately determined according to the energy density, but it is preferable to design with the maximum thickness that can obtain expected heat dissipation characteristics.

Further, in the non-aqueous secondary battery of this embodiment, for example, the flat shape of the battery container may have various shapes such as a square shape, a circular shape, and an oval shape. Although it is a rectangle, it may be a polygon such as a triangle or a hexagon. Further, it may be formed in a tubular shape such as a thin cylinder. In the case of a cylinder, the thickness of the cylinder is the thickness here. Further, from the viewpoint of ease of manufacturing, the flat shape of the battery has a rectangular front and back surfaces, and a notebook shape as shown in FIG. 1 is preferable.

In this embodiment, the battery container is composed of a flat plate-shaped upper lid and a drawn bottom container, the upper lid 1 is provided with a portion made of an aluminum alloy as a main member, and the bottom container 2 is of high purity. It has a portion made of aluminum metal as a main member. The entire battery container does not necessarily have to be made of an aluminum-based material, and may be provided with a portion made of an aluminum-based material as a main constituent member. However, in order to sufficiently exert the effects of the present invention described later, it is preferable that 80% or more of the entire battery container is made of an aluminum-based material, and more preferably 90% or more.

The bottom container material of the battery container is preferably made of high-purity aluminum having an Al component content of 99% by weight or more, and more preferably 99.5% or more. Al component content is as low as less than 99%, M
When the ratio of n and Cu components is high, the mechanical strength is increased but the elongation rate is decreased. In that case, a cutting occurs in the drawing process, and it is difficult to draw deeply. Further, when the R of each corner is designed to be small in order to increase the energy density of the battery, there is a high possibility that a material that is difficult to stretch will be broken or cracked by drawing. From this viewpoint, as a material for the battery bottom container to be drawn, the Al component content is 99
It is desirable to use high-purity aluminum having a high elongation percentage of not less than wt% as the main component.

The aluminum alloy material used for the upper lid of the battery container is, for example, Si, Fe, Cu, Mn, M.
An alloy of one or more metals selected from g, Cr, Zn, Ti, etc. and aluminum can be used. With respect to the components of the Al-Mn alloy, the content of the Mn component is preferably 0.5% by weight to 2.0% by weight. If the Mn component is less than 0.5% by weight, the mechanical strength and the rigidity in a large size will be low. In addition, the formability and the laser welding characteristics are deteriorated. On the other hand, even if it exceeds 2.0% by weight, the effect of improving the strength does not increase so much and the possibility of cracking due to the appearance of a coarse intermetallic compound increases. The content of the Mg component in the Mg-Al alloy is preferably 0.02% by weight to 0.8% by weight. When the Mg component is 0.8% by weight or more, welding defects such as cracks and holes are likely to occur when laser welding the battery container.

As described above, by combining the upper container made of an aluminum alloy and the bottom container made of high-purity aluminum in the battery container, the battery can have both mechanical strength, laser weldability and high energy density. It will be possible.

The thicknesses of the upper lid 1 and the bottom container 2 constituting the battery container are appropriately determined depending on the use of the battery, the material of the battery case, etc., and are not particularly limited, but preferably,
The thickness of 80% or more of the surface area of the battery (the thickness of the widest part of the battery container) is 0.2 mm or more. If the thickness is less than 0.2 mm, there is a problem that the strength required for battery production cannot be obtained. From this viewpoint,
The thickness is more preferably 0.3 mm or more, and further preferably 0.4 mm or more. The thickness of the same part is 1m
It is preferably m or less. If this thickness exceeds 1 mm, the force to press down the electrode surface becomes large, but it is not desirable because the internal volume of the battery decreases and sufficient capacity cannot be obtained, or the weight becomes heavy. It is preferably 0.7 mm or less.

As described above, the battery container is made of aluminum or an alloy mainly composed of aluminum, and the thickness of the non-aqueous secondary battery is designed to be less than 12 mm, so that this battery has a large capacity of 30 Wh or more and 180 Wh. Even when high-rate charging / discharging is performed in the case of having a high energy density of 1 / l, excellent heat dissipation characteristics can be realized and an increase in battery temperature can be suppressed. Therefore, heat storage of the battery due to internal heat generation can be reduced, and as a result, thermal runaway of the battery can be suppressed, and a non-aqueous secondary battery excellent in reliability and safety can be provided. In particular, in the present embodiment, since the battery container is made of an aluminum-based material, it is possible to reduce the weight of the battery container as compared with a conventional battery container made of stainless steel or the like,
This makes it possible to reduce the weight of the entire battery. As a result, although it depends on the battery thickness and the battery surface area, the weight energy density is 1.
It can be improved about 2 to 1.5 times.

On the other hand, a large rectangular battery having a general shape,
Alternatively, when the battery container of a cylindrical battery or the like is changed from, for example, stainless steel to an aluminum-based material, the volume ratio of the battery container material to the entire battery is smaller than that of the flat battery, and therefore the weight energy is reduced. The density improvement is about 1.2 times at most.

As described above, in a non-aqueous secondary battery having a flat shape with a thickness of less than 12 mm, a large capacity of 30 Wh or more and a high energy density of 180 Wh / l or more, aluminum or aluminum is mainly used as a battery container. The effect of applying the alloy is extremely large.

By the way, in the case of using aluminum or an alloy mainly composed of aluminum, as compared with stainless steel and iron which are generally used for the battery container, the force for sandwiching and pressing the electrode surface is weakened, so that the internal resistance is increased. Or, the cycle life may be shortened to affect the battery performance. In particular, in order to obtain a high volumetric energy density in a battery having a thickness of 8 mm or less, it is necessary to reduce the thickness of the material forming the battery container. However, if this is done, the above-mentioned deterioration of the battery characteristics tends to occur. Become. To solve these problems, as described below, by sealing the inside of the battery so that the pressure is less than atmospheric pressure, even if aluminum or an alloy mainly containing aluminum is used for the battery container, It was found that the characteristics equivalent to stainless steel and iron can be obtained without increasing the value.

In order to keep the internal pressure of the completed battery below atmospheric pressure, the positive electrode 101a, the negative electrode 101b,
101c, the separator 104 and the non-aqueous electrolyte are housed in the battery container, and the final sealing process of the battery container is performed in a state where the pressure inside the battery container is less than atmospheric pressure. This final sealing step is preferably performed after at least one charging operation. This is because gas may be generated inside the electrolyte due to decomposition of the electrolytic solution at the initial stage of the first charging, and in this case, if the final sealing step is performed below atmospheric pressure without performing the charging operation, the subsequent first sealing This is because the inside of the battery becomes pressurized (atmospheric pressure or higher) due to the charging operation, the thickness of the battery becomes thick, and the internal resistance and capacity of the battery vary, so that stable cycle characteristics may not be obtained. In particular, when a liquid electrolyte using graphite for the negative electrode and lithium composite oxide for the positive electrode is used, gas is easily generated.

For this charging operation, various conditions are adopted depending on the types of positive electrode material, negative electrode material, separator, electrolytic solution, etc. used in the battery, the water content and impurities of these materials, the voltage at which the battery is used, etc. However, for example, the battery is charged up to the working voltage at a rate of about 4 to 8 hours, a constant voltage is applied if necessary, and further discharged to the normal lower limit voltage at a rate of about 8 hours. Alternatively, a final sealing step is performed after this charging operation. Further, it may be sealed after performing only the charging operation less than the capacity of the battery, or various charging operations such as sealing after repeating charging / discharging twice or more are possible. It is important to keep the internal pressure of the battery below below atmospheric pressure.

As described above, in the present embodiment, after the charging operation is performed to generate the gas, the gas is vented and the final sealing step is performed at a pressure lower than atmospheric pressure, so that aluminum or an alloy mainly containing aluminum is used for the battery. It is possible to solve the problem that the container tends to swell when used as a container. In this case, when performing the first charging operation, the pressure inside the battery is not particularly limited,
It is preferable to carry out the inside of the battery under atmospheric pressure.

The method for keeping the inside of the battery below atmospheric pressure is not particularly limited, but specifically, it can be carried out as follows.

First, as shown in FIG. 2, the positive electrode 101a,
After accommodating an electrode laminated body or the like obtained by laminating the negative electrodes 101b and 101c and the separator 104 in the upper lid 1 and the bottom container 2, the outer peripheral portions of the upper lid 1 and the bottom container 2 are welded. Next, the electrolytic solution is injected into the battery container through the injection port 5 shown in FIG. Then, for temporary sealing, the above-mentioned aluminum-modified polypropylene laminate film, aluminum-
The injection port 5 is once sealed using a heat-sealing type sealing film 6 having a low water permeability, which is represented by a modified polyethylene laminate film, and then the sealing film 6 is removed after charging at least once as described above. . Note that the temporary sealing method is not limited to the above-described example, and the inlet 5 may be temporarily sealed by using, for example, a screw or the like, and a state in which moisture is removed, for example, air is shut off. In the above environment or in a dry atmosphere having a dew point of −40 ° C. or lower, the above charging operation may be performed without sealing.

Next, as the final sealing step, the sealing film 6 is heat-sealed. The method used in the final sealing step is not limited to heat-sealing the sealing film,
The metal plate or foil may be welded, or the cock may be closed after the cock is attached to the battery container to reduce the pressure in the battery to a predetermined pressure (less than atmospheric pressure).

In the final sealing step described above, the pressure inside the battery is set to be less than atmospheric pressure, but 8.66 × 10 ⁴
Pa (650 Torr) or less is preferable,
It is more preferable to set it to not more than 7.33 × 10 ⁴ Pa (550 Torr). This pressure is determined according to the internal pressure required for the finally completed battery. It is preferable that the portion forming the injection port 5 is on either the front surface or the back surface except the outer peripheral portion 5 mm of the battery. In the case of the flat shape shown in FIG. 1, it is more preferable to provide it in a dead space between the positive electrode terminal 3 and the negative electrode terminal 4 arranged in the upper lid 1 from the viewpoint of ensuring the energy density by effectively utilizing the space. In addition, after the final sealing step, in the metal battery container, it is preferable to cover parts other than the positive and negative electrode external terminals with an insulating film or the like. This is because it is possible to prevent an external short circuit due to contact between the both-pole external terminals and the metal container when a module or the like in which batteries are arranged in a stack is assumed or in normal handling.

[0051]

EXAMPLES The present invention will now be described more specifically by showing examples of the present invention.

Example (1) 100 parts by weight of LiMn ₂ O ₄ , 8 parts by weight of acetylene black, polyvinylidene fluoride (PVDF) 3
Part by weight was mixed with 100 parts by weight of N-methylpyrrolidone (NMP) to obtain a positive electrode mixture slurry. The slurry was applied on both sides of an aluminum foil having a thickness of 20 μm to be a current collector, dried and then pressed to obtain a positive electrode. FIG. 3A is an explanatory diagram of the positive electrode. In this embodiment, the positive electrode 101a has a coating area (W1 × W2) of 262.5 × 192 mm ² and is coated on both sides of a 20 μm current collector with a thickness of 110 μm. As a result, the electrode thickness t is 240 μm. Further, the short side of the electrode is provided with a positive electrode collector piece 106a to which no electrode material is applied, and a hole having a diameter of 3 mm is formed in the center thereof.

(2) Graphitized mesocarbon microbeads (MCMB, manufactured by Osaka Gas Chemicals, product number 6-28) 10
0 parts by weight and 10 parts by weight of PVDF were mixed with 90 parts by weight of NMP to obtain a negative electrode mixture slurry. After coating the slurry on both sides of a copper foil having a thickness of 14 μm as a current collector and drying,
It pressed and the negative electrode was obtained. FIG. 3B is an explanatory diagram of the negative electrode. The coating area (W1 × W2) of the negative electrode 101b is
It is 267 × 195 mm ² , and is applied to both sides of a 14 μm current collector in a thickness of 90 μm. As a result, the electrode thickness t is 194 μm. Further, a negative electrode current collector piece 106b not coated with an electrode material is provided on the short side of the electrode, and a hole having a diameter of 3 mm is formed in the center thereof.
Further, a single-sided electrode having a thickness of 104 μm was prepared by applying the composition on only one surface by the same method and by otherwise performing the same method. The single-sided electrodes are arranged on both outer sides of the electrode laminate of item (3) (101c in FIG. 2).

(3) As shown in FIG. 2, 8 sheets of the positive electrode and 9 sheets of the negative electrode (2 sheets on one side on the inner side) obtained in the above item (1) were used as a separator A104a (rayon system, basis weight 12.6 g / m ² ). And separator B104b (polyethylene microporous membrane; basis weight 1
3.3 g / m ² ) and the separator B 104 a is further laminated on the outer side of the outer negative electrode 101 c for insulation with the battery container.
Was placed to prepare an electrode laminate. In addition, the separator 1
No. 04 was arranged such that the separator A 104a was on the positive electrode side and the separator B 104b was on the negative electrode side.

(4) As shown in FIG. 4, the bottom container 2 constituting the battery container is a thin plate (Al purity 99.50% or more) made of high-purity aluminum 1050 (symbol according to JIS H 4000) having a thickness of 0.5 mm. ) Was drawn into a tray with a depth of 5 mm and four corners R3. Top lid 1
Is a thin plate made of Mn-Al alloy 3003 having a thickness of 0.5 mm, which is punched from a flat plate. Further, as shown in FIG. 4, a positive electrode terminal 3 made of aluminum and a negative electrode terminal 4 made of copper (a head portion of 6 mmφ and a screw portion of the tip M3) were attached to the upper lid 1. The positive electrode terminal 3 and the negative electrode terminal 4 were insulated from the upper lid 1 by a Teflon (registered trademark) gasket.

(5) The screw portion of the positive electrode terminal 3 is inserted into the hole of each positive electrode current collector piece 106a of the electrode laminate prepared in the above (3), and the negative electrode terminal 4 is inserted into the hole of each negative electrode current collector piece 106b. After inserting the screw part of each of them and fastening a nut made of aluminum and a nut made of copper, respectively, the electrode laminated body is fixed to the upper lid 1 with an insulating tape, and the overlapping portion A of the upper lid 1 and the flange portion of the bottom container 2 shown in FIG. Was laser-welded from the top cover over the entire circumference. Then, from a liquid injection port 5 (6 mmφ), a solvent prepared by mixing ethylene carbonate and diethyl carbonate at a 1: 1 weight ratio as an electrolytic solution was added with LiPF _{6 at} a concentration of 1 mol / l.
The solution in which was dissolved was injected. Subsequently, the liquid injection port 5 was temporarily closed under atmospheric pressure using a temporary fixing bolt.

(6) This battery was charged to a voltage of 4.2 V with a current of 5 A, and then a constant-current constant-voltage charge for applying a constant voltage of 4.2 V was performed for 8 hours, followed by a constant current of 5 A for 3. 0V
Discharged up to.

(7) The temporary fixing bolt attached to the battery was removed, and 4.00 × 10 ⁴ Pa (300 Tor)
Under reduced pressure of r), thickness 0.08 punched to 12 mmφ
mm of the aluminum foil-modified polypropylene laminated film, the sealing film 6, the temperature 250 ~ 350 ℃,
Pressure 98.1 to 294 kPa (1 to 3 kg / cm ² ),
The liquid injection port 5 was finally sealed by heat fusion under a pressurizing time of 5 to 10 seconds to obtain a flat battery having a thickness of 6 mm. A trial production of 10 cells in total was carried out, but no liquid leakage occurred.

Subsequently, this battery was fed with a current of 5 A to 4.2 V
Charging is performed for up to 8 hours, and then a constant current constant voltage charging in which a constant voltage of 4.2 V is applied is performed for 8 hours, followed by a constant current of 5 A for 3.
It was discharged to 0 V and the capacity was confirmed. The discharge capacity calculated by this was 27 Ah. This battery has an energy capacity of 100 Wh and a volume energy density of 265 Wh /
1, and the weight energy density was 140 Wh / Kg.
When discharged with a constant current of 10 A, the discharge capacity is 2
It was 4.9 Ah.

Comparative Example 1 A battery was assembled in the same manner as in the above Example except that both the bottom container 2 and the top lid 1 were made of a highly pure aluminum 1050 thin plate having a thickness of 0.5 mm. Probably because of a small crack generated in 2 cells, a small amount of liquid leakage was confirmed during the column liquid process in 2 cells out of the 10 prototype cells.
In addition, when a drop test was performed on a concrete surface from a height of 1.9 m using the same battery, the flange corners of some of the batteries were greatly deformed and were in a state of being on the verge of opening. From the above, both the bottom container 2 and the top lid 1 have a thickness of 0.
When a 5 mm aluminum 1050 thin plate material was used, there was a problem in airtightness during laser welding and mechanical strength during use.

Comparative Example 2 A battery was assembled in the same manner as in the above-described example except that both the bottom container 2 and the upper lid 1 were made of a thin plate made of aluminum alloy 3003 having a thickness of 0.5 mm.
The bottom container was squeezed for a total of 10 cells at m and corner R2. However, a small hole was found near the corner in 1 of 10 containers. Therefore, when the above alloy is used, it is necessary to increase R a little more. However, if R is designed to be large, the internal effective volume of the entire battery will decrease,
There is a problem that the energy density of the battery decreases.

[0062]

As is apparent from the above, according to the present invention, a flat non-aqueous secondary having a flat shape with a thickness of less than 12 mm, a large capacity of 30 Wh or more and a volume energy density of 180 Wh / l or more. In the battery, the weight of the battery container can be reduced by combining the battery container with an aluminum alloy for the upper lid and the high-purity aluminum for the bottom container as main constituent members, and as a result, even for a large area flat shape. Regardless, it is possible to provide a non-aqueous secondary battery that realizes a high weight energy density. Further, by combining the above aluminum-based materials, the upper lid can be provided with mechanical strength and laser weldability, and the bottom container can be deeply processed with a small radius R, so that a battery design with a higher volume energy density becomes possible.

[Brief description of drawings]

FIG. 1 is a diagram showing a plan view and a side view of a non-aqueous secondary battery for a power storage system according to an embodiment of the present invention.

FIG. 2 is a side view showing a configuration of an electrode laminated body housed inside the battery shown in FIG.

FIG. 3 is a plan view of a positive electrode, a negative electrode, and a separator that form the laminated body shown in FIG.

FIG. 4 is a cross-sectional view showing a state in which an upper lid and a bottom container of the battery shown in FIG. 1 are separated.

[Explanation of symbols]

1 Top cover 2 bottom containers 3 Positive terminal 4 Negative electrode terminal 5 Injection port 6 sealing film 101a Positive electrode (both sides) 101b Negative electrode (both sides) 101c Negative electrode (one side) 104 separator 105a Positive electrode current collector 105b Negative electrode current collector 106a Positive electrode current collector piece 106b Negative electrode current collector piece

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shizukuni Yada             4-1-2 Hirano-cho, Chuo-ku, Osaka-shi, Osaka Prefecture               Kansai Research Institute of Technology (72) Inventor Hiroyuki Tajiri             4-1-2 Hirano-cho, Chuo-ku, Osaka-shi, Osaka Prefecture               Within Osaka Gas Co., Ltd. F term (reference) 5H011 AA03 BB05 CC06 DD03 KK01                       KK04                 5H029 AJ03 AK03 AL07 AM03 AM05                       AM07 BJ03 CJ16 DJ02 DJ16                       EJ01 HJ04 HJ15 HJ19                 5H050 AA08 BA17 CA09 CB08 FA17                       HA19

Claims (11)

[Claims] 1. A positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte containing a lithium salt are contained in a battery container and have a thickness of 1
It has a flat shape of less than 2 mm and its energy capacity is 3
In a non-aqueous secondary battery having a volume energy density of 0 Wh or more and a volume energy density of 180 Wh / l or more, the battery container is composed of a flat plate-shaped top cover and a drawn bottom container, and the top cover is made of an aluminum alloy. A non-aqueous secondary battery provided as a main member, wherein the bottom container is provided with a portion made of high-purity aluminum as a main member. 2. The non-aqueous secondary battery according to claim 1, wherein the bottom container of the battery container is made of high-purity aluminum containing 99% by weight or more of an Al component. 3. The non-aqueous secondary battery according to claim 2, wherein the upper lid of the battery container is made of an aluminum alloy containing 0.5 wt% to 2.0 wt% of Mn component. 4. The upper lid of the battery container is 0.02.
The non-aqueous secondary battery according to claim 3, wherein the non-aqueous secondary battery is composed of an aluminum alloy containing a Mg component in a weight percentage of 0.8 wt%. 5. The non-aqueous secondary battery according to claim 1, wherein the pressure inside the battery container is less than atmospheric pressure. 6. The pressure inside the battery container is at least 1.
The non-aqueous secondary battery according to claim 5, wherein the non-aqueous secondary battery is made to have a pressure lower than atmospheric pressure by being finally sealed after being charged once and having a pressure in the battery container lower than atmospheric pressure. 7. The pressure inside the battery container is 8.66 × 1.
The non-aqueous secondary battery according to any one of claims 1 to 6, which has a pressure of 0 ⁴ Pa or less. 8. The non-aqueous secondary battery according to claim 1, wherein the negative electrode contains a substance capable of doping and dedoping lithium. 9. The non-aqueous secondary battery according to claim 1, wherein the positive electrode contains manganese oxide. 10. The non-aqueous secondary battery according to claim 1, wherein the top and bottom surfaces of the flat shape are rectangular. 11. The non-aqueous secondary battery according to claim 1, wherein the battery container has a plate thickness of 0.2 mm or more and 1 mm or less.