JP2001216953A - Nonaqueous type secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous type secondary cell of compressed form featuring the large size and the safety. SOLUTION: For the nonaqueous type secondary battery in which a cathode, an anode, a separator and a nonaqueous electrolyte containing lithium salt are equipped, and which is sealed into a battery container, the cathode terminal 3 and the anode terminal 4 which are fixed at the designated location of the battery container are prepared at least by more than one for either terminal, of which the terminals of the same polarity are connected together thorough the connectors 33 and 34.

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 for resource saving and global environmental problems, a home-use decentralized power storage system for late-night power storage and power storage for photovoltaic power generation has been developed. Power storage systems are attracting attention. For example, JP-A-6-86463 discloses that
As a system capable of supplying energy to an energy consumer under optimum conditions, a total system combining electricity supplied from a power plant, gas cogeneration, a fuel cell, a storage battery, and the like has been proposed. A secondary battery used in such a power storage system has an energy capacity of 10
Unlike small secondary batteries for portable devices of Wh or less, large batteries having large capacities are required. For this reason, in the above-described power storage system, a plurality of secondary batteries are stacked in series, and usually used as a battery pack having a voltage of, for example, 50 to 400 V. In most cases, a lead battery is used.

On the other hand, in the field of small rechargeable batteries for portable equipment, nickel-metal hydride batteries and lithium rechargeable batteries have been developed as new types of batteries in order 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. In particular, lithium-ion batteries
It has the potential of a volume energy density exceeding 350 Wh / l, and its reliability, such as safety and cycle characteristics, is superior to a lithium secondary battery using lithium metal as a negative electrode. Prolonged.

[0004] In response to this, in the field of large-sized batteries for power storage systems, lithium-ion batteries have been targeted as candidates for high-energy density batteries, and lithium battery power storage technology research associations (LIBES) and others have been vigorously developing them. Have been.

The energy capacity of these large lithium ion batteries is about 100 Wh to 400 Wh, and the volume energy density is 200 to 300 Wh / l, which is at the level of a small secondary battery for portable equipment. Its shape is
Diameter 50mm-70mm, length 250mm-450mm
And a rectangular prism having a thickness of 35 mm to 50 mm or an oblong prism or the like are typical.

[0006] As for the thin lithium secondary battery, for example, a film battery (for example, Japanese Patent Application Laid-Open Nos. Hei 5-159575 and Hei 7-15975) in which a thin film having a thickness of 1 mm or less in which metal and plastic are laminated is accommodated in a thin exterior. -5
No. 7788), a small rectangular battery having a thickness of about 2 mm to 15 mm (JP-A-8-195204, JP-A-8-195204).
138727, JP-A-9-213286, etc.) are known. The purpose of these lithium secondary batteries is to respond to the miniaturization and thinning of portable devices. For example, an area of about JIS A4 size with a thickness of several mm that can be stored on the bottom surface of a portable personal computer. Japanese Patent Application Laid-Open No. 5-28310 discloses a thin battery.
No. 5), since the energy capacity is 10 Wh or less, the capacity is too small for a secondary battery for a power storage system.

[0007]

Generally, an external terminal structure of a small cylindrical lithium ion battery for portable equipment has one polarity conductively connected to a can constituting a battery container, and the other polarity of the battery container. These cans and lids are electrically connected to the lids, and the cans and the lids are caulked with an insulating resin gasket and sealed and fixed, so that the cans and the lids also serve as external terminals. Also, for a small-sized rectangular lithium ion battery, it is necessary to weld the container and the lid together to seal them, so that one pole terminal is often fixed by caulking to the center of the lid via an insulating resin. Therefore, in the case of a small rectangular type, one polarity is electrically connected to the can and the other polarity is electrically connected to the pole terminal provided on the lid.

[0008] In both the small cylindrical type and the small square type, the connection to the equipment side includes a terminal provided on the container bottom and the lid or a terminal comprising the lid and a gold-plated equipment side each having high corrosion resistance. A method in which terminals are connected by pressure welding and conductive, a method in which a metal piece is spot-welded to a terminal provided on a container bottom and a lid, or a terminal composed of a lid, are used. In most cases, these connection schemes are used for portable devices that normally pass only up to about 5 A of current.

However, for a large battery having an energy capacity exceeding 30 Wh, it is necessary to pass a larger current, so that it is stronger and more reliable than the connection method generally used for the above-mentioned small battery. High connection method is required. This is especially true when a large battery is used as an assembled battery. Therefore, in general, for connection of a large-sized lithium ion battery, a female screw or a male screw is applied to an external terminal in advance. At the time of connection, a method is used in which a device-side terminal plate or a wire with a crimp terminal is fastened and fixed with a nut or bolt. As another example, a method is also used in which a column-shaped portion is provided in a part of the terminal, a split-type set collar is fitted, and the terminal is tightened in a direction to reduce the inner diameter.

However, as described above, one for each electrode terminal.
In the method of tightening and fixing with bolts and nuts, when external force is applied to the device-side terminal plate or a thick wire with a crimp terminal in the rotating direction to loosen the screw at the time of assembling or use, the screw tightening portion is loosened and the contact resistance increases. When a large current is applied to the poor contact portion, heat is generated, and it is expected that the heat will eventually be transmitted to the battery, causing a very dangerous situation.

As described above, a terminal component of a large-sized lithium ion battery generally has an external terminal formed by combining an external terminal with a cylinder having a female screw or a male screw beforehand.
It is fixed to the battery container via a ring or the like. When assembling or using, if an external force in the rotating direction that tightens the screw is applied more than necessary to the device-side terminal plate or the thick electric wire with the crimp terminal, the fixing part idles on the battery container, and the connection structure inside the battery is reduced. It can break and, in the worst case, cause an internal short circuit. An internal short circuit in a large battery is often accompanied by a large exothermic reaction, which may cause an extremely dangerous situation more than the heat generation phenomenon due to the poor contact with the outside.

For example, regarding a cylindrical large-sized lithium ion battery, as described in JP-A-9-92250,
The seal is maintained by tightening the O-ring, and the cap and pole are idled inside the cap by inserting the detent pin into the hole provided in the pole where the internal pole plate is collectively connected. There are examples of preventing destruction of objects. However, the outer terminal is fixed by tightening a bolt to one terminal of a circular casting die having a female screw. Therefore, when any external force is applied to the terminal fitting from the outside in the rotational direction, it is impossible to prevent poor contact on the outside due to loosening.

A structure in which an electrode terminal is fixed to a battery case lid with a hermetic seal by a difference in thermal expansion ratio through a glass seal is generally used in a large lithium-based battery.
However, since the direction of the compressive force is one direction, there is a disadvantage that the compressive force is weak against an external force in a direction perpendicular to the direction or a rotational direction. For example, as described in Japanese Patent Application Laid-Open No. 11-7923, even if the above-described method is used, by filling a space surrounded by a metal flange and a battery cover with a glass material, it is possible to prevent impact in the vertical direction. A withstand structure has been devised. However, it is weak to the force in the rotating direction, and if a strong external force is applied, the terminal may idle inside or outside the glass seal part, and the part connecting the current collector inside the battery may be damaged. .

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems by providing an excellent safety device which can surely prevent an internal short circuit due to internal damage and abnormal heat generation due to a poor contact at an outer terminal connection portion during manufacture or use. An object of the present invention is to provide an aqueous secondary battery.

A further object of the present invention is to provide a highly safe non-aqueous secondary battery having a large capacity of 30 Wh or more and a volume energy density of 180 Wh / l or more, low internal resistance and excellent heat radiation characteristics. It is in the thing.

[0016]

SUMMARY OF THE INVENTION The object of the present invention is to provide a non-aqueous secondary battery, which is provided with a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte containing a lithium salt and is hermetically sealed in a battery container. Wherein at least one of the positive electrode terminal and the negative electrode terminal fixed at a predetermined position has two or more electrode terminals, and these two or more terminals are connected and fixed by a connecting member. This is achieved by a non-aqueous secondary battery.

It is preferable that the two or more electrode terminals and the connecting member are formed integrally. Also,
It is preferable that the two or more electrode terminals are hermetically fixed by caulking and fixing to the battery container via a resin gasket.

It is preferable that the portion where the two or more electrode terminals are caulked and fixed has a shape including a circle.

The shape of the battery container is preferably rectangular.

The non-aqueous secondary battery has an energy capacity of 30 Wh or more and a volume energy density of 180 Wh / l.
The above flat shape is preferred.

It is preferable that the non-aqueous secondary battery has a flat shape with a thickness of less than 12 mm.

The thickness of the battery container is 0.2 mm or more and 1
mm or less.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A non-aqueous secondary battery according to one embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a flat rectangle (note type) according to an embodiment of the present invention.
FIG. 2A is a plan view and FIG. 2B is a side view showing the outer shape of the non-aqueous secondary battery for a power storage system. FIG. 2 is a side view showing the configuration of an electrode laminate housed inside the battery shown in FIG. It is sectional drawing. The same reference numerals denote the same parts throughout the drawings.

As shown in FIGS. 1 and 2, the non-aqueous secondary battery of the present embodiment has a battery case (battery container) in which an upper lid 1 and a bottom container 2 are brought into close contact with each other, and a battery case in the battery case. A plurality of positive electrodes 101a, negative electrodes 101b,
1c and an electrode laminate comprising the separator 104. In the case of a flat nonaqueous secondary battery as in this embodiment, the positive electrode 101a and the negative electrode 101b (or the negative electrode 101c disposed on both outer sides of the stacked body) are provided with, for example, a separator 104 as shown in FIG. The layers are alternately arranged and stacked through the interposition, but the present invention is not particularly limited to this arrangement,
The number of layers and the like can be variously changed according to the required capacity and the like.

The positive electrode current collector 105a of each positive electrode 101a is:
Similarly, the negative electrode current collector 105b of each of the negative electrodes 101b and 101c is electrically connected to the two negative electrode terminals 4. The positive electrode terminal 3 and the negative electrode terminal 4 are attached while being insulated from the battery case, that is, the upper lid 1. The top cover 1 and the bottom container 2 are shown in FIG.
At the point A shown in the enlarged sectional view in the middle, the upper lid is melted and welded all around. An electrolyte inlet 5 is opened in the upper lid 1. After the electrolyte is injected, a thermoplastic film 6 having a low moisture permeability represented by an aluminum-modified polypropylene laminated film and an aluminum-modified polyethylene laminated film is formed. And sealed by heat fusion.

In the closing step, it is preferable that the pressure in the battery is lower than the atmospheric pressure. Preferably 650torr
Hereinafter, it is more preferably performed at 550 torr or less. This pressure is determined in consideration of the separator used, the type of electrolyte, the material and thickness of the battery can, and the shape of the battery. When the internal pressure is equal to or higher than the atmospheric pressure, the battery becomes larger than the designed thickness or the thickness variation becomes large, which causes the internal resistance and the capacity of the battery to vary.

The shape of the non-aqueous secondary battery shown in FIGS. 1 and 2 is, for example, 300 mm in length × 210 mm in width × 6 mm in thickness, and LiMn ₂ O ₄ , negative electrode 101 b,
In the case of a lithium secondary battery using a carbon material for 01c, for example, it can be used for a power storage system.

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. A lithium composite cobalt oxide, a lithium composite nickel oxide, a lithium composite manganese oxide, or a mixture thereof is used. Further, a system in which one or more different metal elements are added to these composite oxides can be used, and a battery with high voltage and high capacity can be obtained, which is preferable. When importance is placed on safety, a manganese oxide having a high thermal decomposition temperature is preferable. Examples of the manganese oxide include a lithium composite manganese oxide represented by LiMn ₂ O ₄ , a system in which one or more different metal elements are added to these composite oxides, and an excess of lithium, oxygen, etc. in excess of the stoichiometric ratio. LiMn
₂ O ₄ .

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. A material capable of doping and undoping lithium can be used for safety and cycle life. This is preferable because the reliability of the device improves. As a material capable of doping and undoping lithium, a graphite-based material, a carbon-based material, a tin oxide-based material, which is used as a negative electrode material of a known lithium ion battery,
Examples thereof include metal oxides such as silicon oxides, and conductive polymers typified by polyacene-based organic semiconductors. In particular, from the viewpoint of safety, a polyacene-based substance that generates a small amount of heat at about 150 ° C. or a material containing the same is desirable.

Although the structure of the separator 104 is not particularly limited, a single-layer or multi-layer separator can be used, and at least one sheet is preferably made of a nonwoven fabric, thereby improving cycle characteristics. Separator 1
04 is not particularly limited, for example, polyethylene, polyolefin such as polypropylene,
Polyamide, kraft paper, glass and the like can be mentioned, and polyethylene and polypropylene are preferred from the viewpoint of cost, water content and the like. When polyethylene or polypropylene is used as the separator 104, the basis weight of the separator is preferably 5 g / m ² or more and 30 g / m ² or less, more preferably 5 g / m ² or more and 20 g / m ² or less. More preferably, it is 8 g / m ² or more and 20 g / m ² or less. If the basis weight of the separator exceeds 30 g / m ² , the separator becomes too thick or the porosity decreases, and the internal resistance of the battery increases.
If it is less than / m ² , it is not preferable because practical strength cannot be obtained.

As the electrolyte of the non-aqueous secondary battery of the present embodiment, a known non-aqueous electrolyte containing a lithium salt can be used, which is appropriately determined according to the conditions of use such as a positive electrode material, a negative electrode material, and a charging voltage. , More specifically LiPF ₆ ,
LiBF ₄ , LiClO _{4 and} other lithium salts are converted to organic solvents such as propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, dimethoxyethane, γ-butyl lactone, methyl acetate, methyl formate, or a mixed solvent of two or more of these. Examples thereof include those dissolved in a solvent. Further, the concentration of the electrolytic solution is not particularly limited, but is generally practically 0.5 mol / l to 2 mol / l. Naturally, the electrolytic solution has a water content of 100 ppm or less. Preferably, it is used. In addition, the non-aqueous electrolyte used in this specification means a concept including a non-aqueous electrolyte and an organic electrolyte, and also a concept including a gel or solid electrolyte.

The non-aqueous secondary battery configured as described above can be used for home power storage systems (nighttime power storage, cogeneration, solar power generation, etc.), power storage systems for electric vehicles, etc. It can have capacity and high energy density. In this case, the energy capacity is preferably 30 Wh or more (generally 500 Wh or less), more preferably 50 Wh or more, and the energy density is preferably 180 Wh / l or more (generally 400 Wh / l).
h / l or less), and more preferably 200 Wh / l or more. When the energy capacity is less than 30 Wh or when 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 in order to obtain a sufficient system capacity. In addition, it is not preferable for a power storage system because a compact design is difficult.

By the way, in general, a large lithium secondary battery (energy capacity of 30 Wh or more) for a power storage system can obtain a high energy density, but its battery design is an extension of a small battery for a portable device. Alternatively, the battery has a cylindrical shape, a square shape, or the like having a thickness three times or more that of a small battery for a portable device. In this case, heat easily accumulates inside the battery due to Joule heat generated by the internal resistance of the battery during charge / discharge or internal heat generated by the battery due to a change in entropy of the active material due to the entrance and exit of lithium ions. For this reason, the difference between the temperature inside the battery and the temperature near the battery surface is large, and the internal resistance differs accordingly. As a result, the charge amount and the voltage are likely to vary. Also, since a plurality of batteries of this type are used as assembled batteries, the heat storage easiness varies depending on the installation position of the batteries in the system, causing variations among the batteries, and accurate control of the entire assembled battery. It becomes difficult. Furthermore, the battery temperature rises due to insufficient heat radiation during high-rate charging and discharging, etc., and the battery is put in an unfavorable state. Problems such as induction of reliability and, in particular, safety remain.

The flat non-aqueous secondary battery of the present embodiment has a large heat radiation area and is advantageous for heat radiation, so that the above-mentioned problems can be solved. That is, the non-aqueous secondary battery of the present embodiment has a flat shape,
Its thickness is preferably less than 12 mm, more preferably less than 10 mm, even more preferably less than 8 mm. The lower limit of the thickness is practically 2 mm or more in consideration of the filling rate of the electrode and the battery size (the smaller the thickness, the larger the area for obtaining the same capacity). Battery thickness is 12
mm or more, it becomes difficult to sufficiently radiate the heat generated inside the battery to the outside, or the temperature difference between the inside of the battery and the vicinity of the battery surface increases, resulting in a difference in internal resistance.
Variations in the amount of charge and voltage in the battery increase. Although the specific thickness is appropriately determined according to the battery capacity and the energy density, it is preferable to design the thickness so as to obtain the expected heat radiation characteristics.

The shape of the non-aqueous secondary battery of the present embodiment is, for example, that the flat front and back surfaces are square, circular,
Various shapes such as an oval shape can be used. In the case of a square shape, the shape is generally a rectangle, but it can also be a polygon such as a triangle or a hexagon. Further, it may be a cylindrical shape such as a thin-walled cylinder. In the case of a cylindrical shape, the thickness of the cylinder is the thickness referred to here. Further, from the viewpoint of ease of production, the flat front and back surfaces of the battery are preferably rectangular, and a notebook-type shape as shown in FIG. 1 is preferable.

The material used for the top lid 1 and the bottom container 2 serving as the battery case is appropriately selected depending on the use and shape of the battery, and is not particularly limited.
Aluminum and the like are common and practical. Also,
The thickness of the battery case is also appropriately determined depending on the use and shape of the battery or the material of the battery case, and is not particularly limited. Preferably, the thickness of the portion of 80% or more of the battery surface area (the thickness of the portion having the largest area constituting the battery case) is 0.2 mm or more. When the thickness is less than 0.2 mm, the strength required for battery production cannot be obtained, which is not desirable.
m or more. Further, it is desirable that the thickness of the portion is 1 mm or less. When the thickness exceeds 1 mm, the force for pressing down the electrode surface increases, but it is not desirable because the internal volume of the battery is reduced and a sufficient capacity cannot be obtained, or the weight increases, which is not desirable. Preferably it is 0.7 mm or less.

As described above, the thickness of the non-aqueous secondary battery is set to 1
By designing it to be less than 2 mm, for example,
When the battery has a large capacity of 0 Wh or more and a high energy density of 180 Wh / l, the battery temperature rise is small even during high-rate charging and discharging, and excellent heat radiation characteristics can be obtained. Therefore, heat storage of the battery due to internal heat generation is 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.

Next, the electrode terminal structure provided in the non-aqueous secondary battery of the present invention configured as described above will be described in detail. As shown in FIGS. 1 and 3, it is desirable that at least one of the positive electrode terminal 3 and the negative electrode terminal 4 fixed at a predetermined position in advance has two or more terminals.
This number is appropriately designed according to the shape of the battery, the thickness of the battery, the material of the battery container and the lid, the capacity of the battery, and the like. In a large battery having an energy capacity of 30 Wh or more, the number of the positive electrode terminal and the negative electrode terminal is It is more preferable that both of the positive electrode terminal and the negative electrode terminal are provided with two or more terminals. In the present invention, if the number of the plurality of electrode terminals is at least two or more, idling in the rotational direction can be prevented, and in particular three or more terminals may be provided.

At the time of assembling or using the battery, for example, a device side terminal plate 10 having two or more holes 10a formed at positions corresponding to the electrode terminals as shown in FIG. The terminal plate 10 is connected. By arranging two or more electrode terminals as described above, if the connection terminal plate 10 is connected and fixed to the negative electrode terminal 4 and the positive electrode terminal 3 by screws 11 or the like, the connection terminal Even if an external force in the rotating direction is applied to the plate 10, it is possible to prevent a situation in which the screw fastening portion is loosened and the contact resistance increases. In particular, in the case of a power storage system or an electric vehicle that is used for a large battery, it is necessary to assemble a large number of batteries as an assembled battery so as to minimize the size of the entire module. The assembling operation is often a severe operation such as screwing and fixing a large number of connection terminal plates 10 to the electrode terminals of each battery in a narrow space. When connecting another connection terminal plate 10 to a connection terminal plate 10 that has already been screwed, it is easily expected that a hand or a tool will hit the connection terminal plate 10. Since there is a possibility that the screw of the portion is loosened, there is a high effect that two or more electrode terminals are provided to prevent rotation.
Further, the electrode terminals provided with two or more of the battery container so that, when a force in a rotational direction is applied in a direction parallel to the plane direction of the battery container, the terminal cannot be rotated without breaking the fixing portion of the battery container. It is connected and fixed by connecting members 33 and 43 on the outside or inside.

Further, it is more preferable that the molded product is an integrally formed product in which the positive electrode terminal 3 and the connecting member 33 or the negative electrode terminal 4 and the connecting member 43 are integrally formed, because the resistance variation due to the pressure contact does not occur.

The above-mentioned two or more positive electrode terminals 3 and negative electrode terminals 4 can be hermetically fixed by caulking and fixing them to the battery container via resin gaskets 31 and 34 as compared with a glass seal or the like in terms of cost. preferable. In addition, the portion where the positive electrode terminal 3 and the negative electrode terminal 4 provided with two or more are caulked and fixed has a shape including a circle, so that the caulking force is suppressed without uneven distribution, so that the reliability of airtightness is high and more preferable. . This is because, when the flat terminal is swaged with a gasket, the force concentrates on the corner portion, and the pressing force of the straight portion in the direction parallel to the surface is weakened. In particular, as described above, as the thickness of the battery container is reduced to reduce the weight of the battery, the effect becomes more remarkable.

As shown in FIG. 3, the positive electrode terminal 3 has a two-stage cylinder provided on a relay terminal plate constituting a connecting member 33 having a screw hole 34 for electrically connecting a positive electrode current collector inside the battery. It can be made into an integral shape, and two cylindrical portions are stabbed into the battery case upper lid 1 via a resin gasket 31 and deformed from the outside of the battery using a press, and then crimped to fix the battery tightly. Can be. Similarly, the negative electrode terminal 4 can be formed by connecting two terminals by a relay terminal plate constituting the connecting member 43. In the illustrated example, all four terminals of the positive and negative electrodes are all cylindrical, and airtightness can be maintained by a uniform caulking force. In addition, since the two terminals of the positive and negative electrodes are connected by the connecting members 33 and 43 and cannot be rotated, the screw hole 3 is externally provided.
When a screw is tightened with the connection terminal plate 10 (FIG. 6) sandwiched between the positive and negative current collectors 2 and 42, the connecting members 33 and 43 rotate inside the battery even if a large torque is applied. It does not lead to a situation that could damage. Also, for the external connection with the equipment, if the connection terminal plate 10 or the like provided with two holes in advance is fastened and fixed with two screws, the external connection terminal plate 10 is rotated by an external force to cause a contact failure. Such situations can be avoided.

[0043]

The present invention will be described more specifically below with reference to examples of the present invention.

Example 1 (1) 100 parts by weight of LiCo 2 O 4, 8 parts by weight of acetylene black, polyvinylidene fluoride (PVDF)
3 parts by weight were mixed with 100 parts by weight of N-methylpyrrolidone (NMP) to obtain a positive electrode mixture slurry. The slurry was applied to both sides of a 20 μm-thick aluminum foil serving as a current collector, dried, and then pressed to obtain a positive electrode. FIG. 4 is an explanatory diagram of an electrode. In the present embodiment, the coating area (W
1 × W2) is 262.5 × 192 mm 2, and is applied to both surfaces of a 20 μm current collector 105 a with a thickness of 103 μm.
As a result, the electrode thickness t is 226 μm. Also,
On the short side of the electrode, there is an ear portion where the electrode is not applied, and a hole of φ3 is formed.

(2) Graphitized mesocarbon microbeads (MCMB, manufactured by Osaka Gas Chemical Co., Ltd., 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. The slurry was applied on both sides of a 14 μm-thick copper foil serving as a current collector, dried, and then pressed to obtain a negative electrode. This will be described with reference to FIG. The application area (W1 × W2) of the negative electrode 101b or 101c is 267 ×
195 mm2, 108 μm on both sides of 18 μm current collector 105 b
It is applied with a thickness of μm. As a result, the electrode thickness t is 234 μm. Further, on the short side of the electrode, there is an ear portion where the electrode is not applied, and a hole of φ3 is formed. Further, a single-sided electrode having a thickness of 126 μm was formed in the same manner except that the coating was performed on only one side.
The single-sided electrode is disposed outside in the electrode laminate of item (3) (101c in FIG. 2).

(3) Eight positive electrodes obtained in the above (1),
As shown in FIG. 2, nine negative electrodes (two inner surfaces) were used as a separator 104a (polypropylene nonwoven fabric: basis weight 10 g / m ² ) and a separator 104b (polyethylene microporous membrane: basis weight).
3 g / m ² ) (denoted as 104 in FIG. ² ) to form an electrode laminate. Separator
104b was disposed on the positive electrode side. In addition, for insulation with container,
A separator 1 is further provided outside the negative electrode plate 101c outside the laminate.
04b was arranged.

(4) The battery bottom container 2 (see FIG. 1)
A SUS304 thin plate of 0.5 mm was drawn to a depth of 5 mm. Also, the top cover 1 of the battery is made of SUS of 0.5 mm thickness.
It was made of 304 thin plate. The upper lid has a positive electrode terminal made of aluminum and negative electrode terminals 3 and 4 made of copper (6 mmφ, outside M3).
2).

(5) The positive terminal 3 or the negative terminal 4 (see FIG. 3) is a relay terminal plate 33 having a screw hole 34 or 44 for electrically connecting a positive current collector or a negative current collector inside the battery. The two cylindrical portions are provided integrally with each other on the base 43. The two cylindrical portions are stabbed into the battery case upper lid 1 via the resin gasket 31 or 41, and the cylindrical portions are pressed and deformed from the outside by a press. It was fixed airtight by swaging. All four terminals, positive and negative, are all cylindrical and can maintain airtightness with uniform caulking force. In addition, each of the positive and negative electrodes has a structure in which two terminals are formed by integral molding and cannot be rotated.
Even if a large torque is applied when the bolt is tightened to 2 or 42, the relay terminal plate does not rotate inside the battery to damage the positive or negative electrode current collector connection. (6) The holes of the respective positive electrode lugs of the electrode laminate prepared in the above section (3) were inserted into the positive electrode terminal 3, and the holes of the respective negative electrode ears 1 were inserted into the negative electrode terminal 4, and were connected with aluminum and copper bolts, respectively. The electrode laminate was fixed with an insulating tape, and the corner A of FIG. 1 was laser-welded over the entire circumference. Then, electrolyte injection hole 5 (6mmφ)
From a mixture of ethylene carbonate and diethyl carbonate at a weight ratio of 1: 1
A solution in which LiPF6 was dissolved at a concentration of 1 was injected. This battery was punched into a 12 mmφ, and a 0.08 mm thick aluminum foil-modified polypropylene laminate film was 100 t
The electrolyte injection hole 5 was sealed by heat fusion under reduced pressure of orr. (7) For connection of a plurality of batteries to the positive and negative external terminals of the battery obtained as described above, and also for external connection to equipment, etc., two external terminal plates provided with two holes in advance are used. It was fixed with screws. Since the two terminal screws were tightened and fixed, there was no occurrence of a situation in which the outer terminal plate rotated to cause poor contact. When the screws were tightened with a high-torque electric screwdriver with a torque of 4 N · m, the initial internal resistances of the ten batteries manufactured by the above process were measured by the AC method of 1 kHz.
Ω to a maximum of 6.3 Ω, indicating that there is very little variation. One of them is 5A
, And then a constant current constant voltage charging of applying a constant voltage of 4.1 V for 12 hours, followed by a charging of 5 V
When the battery was discharged to 2.5 V at a low current of A, the discharge capacity was 24 Ah and the energy capacity was 86 Wh. Comparative Example 1 A battery was fabricated in the same manner as in Example 1 except for the terminal structure employed in Example 1.

As shown in FIG. 4, the positive electrode terminal 3 or the negative electrode terminal 4 is provided with a relay terminal plate 53 provided with a screw hole 54 or 64 for electrically connecting to a not-shown internal positive electrode current collector or negative electrode current collector. Alternatively, the cylindrical portion is inserted into the battery case upper lid 1 through the hole provided in 63 through the resin gasket 51 or 61, and the cylindrical portion is pressed and deformed from the outside with a press using a press. It was airtightly fixed.

An external terminal plate provided with one hole in advance for connecting a plurality of batteries was fastened and fixed to the positive and negative external terminals of the battery obtained by the above process with one screw. When the screws were tightened strongly with a high torque electric screwdriver at a torque of 4 N · m, it was found that in some cells, the terminals were slightly idle at the gasket portions. Therefore, we changed to using an electric screwdriver with a low torque of 1 N · m or less for screw tightening, but if we worked with a high torque screwdriver, we would move the pre-aligned laminate inside the battery. In the worst case, internal damage such as an internal short circuit or a cut out of an ear may occur, and an extremely dangerous situation may occur. When the initial internal resistance of the ten batteries manufactured by the above-described steps was measured by an alternating current method of 1 kHz, it was found that the initial values varied considerably from a minimum of 6.4Ω to a maximum of 7.8Ω. This is presumably due to the fact that the relay terminal and the electrode terminal are connected only by crimping by crimping.

After stacking the battery contents, the ear holes of each electrode are connected to the electrode terminals, and a terminal plate having a hole for connecting to an external device is screwed to a connection part outside the terminal,
The connecting operation of the module consisting of 20 cells was performed. When the degree of tightening was checked again after the operation, it was found that one cell was loosened. This is considered to be because a tool or the like hits during the work and a force is accidentally applied in the rotation direction of the terminal plate. If a large current was passed without retightening, the contact resistance was increased only at the loosened portion, and it became a heat source, and it was expected that there would be a danger of heating the externally connected battery. .

Comparative Example 2 A battery was manufactured in the same manner as in Example 1 except for the terminal structure employed in Example 1. As shown in FIG. 5, a rectangular flat terminal 3 or 4 having a circular-arc-shaped corner was produced, and was caulked and fixed via a flat gasket 71 or 81 by pressing. Since the upper cover 1 of the battery was a SUS304 thin plate having a thickness of 0.5 mm, distortion occurred in the long side direction, and the flatness of the battery cover could not be maintained. In order to prevent this distortion, it was thought that a thickness of at least 1 mm or more was necessary, though it also depends on the caulking force. Thereafter, the solution was sealed by welding and injected, but a small amount of liquid leaked from a part in the long side direction. If the caulking force is not uniform, it is not possible to maintain the airtightness in this way, and it is expected that liquid leakage from the inside and intrusion of outside air will occur.

[0053]

As is apparent from the above description, according to the present invention, in a flat type battery, particularly in a flat type battery having a large capacity and a high volume energy density, an internal short circuit or an external terminal due to internal breakage during manufacture or use. An excellent non-aqueous secondary battery with high safety that can prevent abnormal heat generation due to poor contact at the connection portion can be provided.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a non-aqueous secondary battery for a power storage system according to the present invention, wherein (a) is a plan view and (b) is a side view.

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

FIG. 3 shows an electrode terminal structure of the non-aqueous secondary battery of FIG. 1,
(A) is a sectional view after assembling, (b) is a positive electrode terminal before assembling,
It is a side view which shows a negative electrode terminal and the connection member connected to them.

FIG. 4 shows an electrode terminal structure used as a comparative example;
(A) is a sectional view after assembling, (b) is an exploded view before assembling,
(C) is a plan view showing the appearance of the battery after assembly.

5A and 5B show a terminal structure used in a comparative example, in which FIG. 5A is a cross-sectional view after assembling, FIG. 5B is an exploded view before assembling, and FIG. It is.

6A and 6B show the non-aqueous secondary battery of FIG. 1 together with a connection terminal plate, FIG. 6A is a plan view of the connection terminal plate, and FIG. 6B is a plan view showing a state where the connection terminal plate is fixed with screws. is there.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Top lid 2 Bottom container 3 Positive electrode terminal 4 Negative terminal 5 Injection port 6 Sealing film 31, 41 Resin gasket 32, 42 Screw hole 33, 43 Connecting member (relay terminal) 34, 44 Screw hole 101a Positive electrode (both sides) 101b Negative electrode (Both sides) 101c Negative electrode (one side) 104, 104a, 104b Separator 105a Positive electrode current collector 105b Negative electrode current collector

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Haruo Kikuta, Inventor 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka Inside Osaka Gas Co., Ltd. (72) Shizukuni Yada 4, Hirano-cho, Chuo-ku, Osaka-shi, Osaka 1-2 F-term in Kansai New Technology Research Institute Co., Ltd. (Reference) 5H022 AA09 BB01 BB03 CC02 CC09 CC12 KK04 5H029 AJ12 AK03 AL02 AL06 AL07 AL16 AM03 AM07 BJ04 CJ01 CJ05 DJ05 HJ04 HJ19

Claims (8)

[Claims] 1. A non-aqueous secondary battery including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte containing a lithium salt and sealed in a battery container, wherein a positive electrode terminal and a negative electrode fixed at predetermined positions of the battery container. A nonaqueous secondary battery, wherein at least one of the terminals has two or more electrode terminals, and the two or more terminals are connected and fixed by a connecting member. 2. The non-aqueous secondary battery according to claim 1, wherein the two or more electrode terminals and the connecting member are formed integrally. 3. The device according to claim 1, wherein the two or more electrode terminals are hermetically fixed by caulking and fixing to the battery container via a resin gasket.
The non-aqueous secondary battery according to 1. 4. The non-aqueous secondary battery according to claim 1, wherein the portion for caulking and fixing the two or more electrode terminals has a shape including a circle. 5. The non-aqueous secondary battery according to claim 1, wherein said battery container has a rectangular shape. 6. The non-aqueous secondary battery has an energy capacity of 30 Wh or more and a volume energy density of 180 Wh /
1 or more flat shape.
The non-aqueous secondary battery according to any one of the above. 7. The non-aqueous secondary battery has a thickness of 12 mm.
The non-aqueous secondary battery according to any one of claims 1 to 6, wherein the non-aqueous secondary battery has a flat shape of less than. 8. The non-aqueous secondary battery according to claim 1, wherein the thickness of the battery container is 0.2 mm or more and 1 mm or less.