JPH10294135A - Hybrid device consisting of electrical double layer capacitor and battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric source in which a pulse discharge characteristic is excellent, especially at a low temperature. SOLUTION: A hybrid device, in which an electrical double layer capacitor 1 and a battery 2 are combined and used as an electric source, is provided. A lithium secondary battery like a lithium ion secondary battery or a lithium polymer secondary battery is preferably used as the battery 2, and it is preferable that the electrical double layer capacitor 1 has a sheet shape and its thickness is in a range of 0.0025 X-0.15 X to an outer diameter (X) of a cylindrical battery, and within a range of 0.07 Y-0.3 Y to a thickness of a square shaped battery.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid device comprising an electric double layer capacitor and a battery, and more particularly, to a hybrid device which can be used as a power supply having good pulse discharge characteristics, particularly low temperature pulse discharge characteristics.

[0002]

2. Description of the Related Art With the recent development of portable electronic devices, the characteristics required for batteries are becoming stricter. For example, devices using batteries have been downsized, and accordingly, batteries have also been required to be downsized. On the other hand, with the multifunctionalization and digitalization of devices, current values are increasing and the use of large current pulses is increasing.

Heretofore, measures have been taken to increase the capacity of primary batteries such as manganese dry batteries and alkaline dry batteries, and to improve load characteristics, etc., and to use nickel-cadmium batteries, nickel-hydrogen storage alloy batteries, lithium ion secondary batteries, lithium This has been addressed by developing high performance secondary batteries such as polymer secondary batteries.

On the other hand, increasing the capacity of a capacitor used for the purpose of backing up a memory separately from the main power supply has been studied, and the electric double layer capacitor has a higher capacity than a ceramic capacitor, an aluminum electrolytic capacitor, a tantalum electrolytic capacitor, or the like. Because of its capacity, those using an electric double layer capacitor as a backup power supply are being put into practical use. Further, attempts have been made to increase the size of this electric double layer capacitor and use it as a power capacitor as an auxiliary power source for instantaneous output of an electric vehicle.

[0005]

Although there is a demand for miniaturization and high performance of batteries, high capacity and high output are generally contradictory performances, and it is difficult to achieve both. For example, an alkaline secondary battery using an alkaline aqueous solution as an electrolyte, such as a nickel-hydrogen storage alloy battery or a nickel-cadmium battery, can easily obtain a high output because of the low resistance of the electrolyte, but cannot obtain a high energy density. It is hard to say, and it is hard to say high capacity.

On the other hand, recent lithium secondary batteries, for example,
Lithium ion secondary batteries and lithium polymer secondary batteries that use polymer electrolytes can store a large amount of energy and can have a high energy density. Difficult to get out. In particular, a mobile phone that requires sufficient characteristics even at a low temperature of -10 ° C or -20 ° C cannot exhibit sufficient characteristics. Therefore, in order to improve this characteristic, a low-boiling point organic solvent is added to lower the viscosity of the electrolytic solution. Will lack.

[0007] The present invention solves the above-mentioned problems of the prior art, and provides pulse discharge characteristics of a secondary battery, particularly a lithium secondary battery such as a lithium ion secondary battery or a lithium polymer secondary battery, especially at a low temperature. The purpose of the present invention is to improve the pulse discharge characteristics of the above.

[0008]

The present invention has solved the above-mentioned problems by integrating the electric double layer capacitor and the battery as a hybrid element and improving the pulse discharge characteristics, particularly, the pulse discharge characteristics at a low temperature.

That is, in a battery having a high internal resistance such as a lithium secondary battery, it is considered that load leveling is facilitated by setting the capacity of the electric double layer capacitor in consideration of the pulse discharge time. .

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The electric double layer capacitor constituting a hybrid element by combining with a battery as described above is preferably in the form of a sheet in order to be integrated with the battery. A flexible material is preferable so that it can be stuck to the outer peripheral portion. When the battery is a cylindrical battery, the thickness of the electric double layer capacitor is 0.0025X to 0.1 with respect to the outer diameter (X) of the battery in order to obtain an effective improvement in load characteristics.
It is preferably in the range of 5X. That is, the thickness of the electric double layer capacitor is set to be 0.
When it is in the range of 0025X to 0.15X, an electric double layer capacitor having an appropriate capacity can be attached while maintaining the same shape without greatly changing the outer diameter of the battery, so that effective pulse discharge is achieved. Although improvement in characteristics is obtained, when the thickness of the electric double layer capacitor is smaller than the above range, the capacity of the electric double layer capacitor may be insufficient, or the reliability of the sealing structure may be reduced,
When the thickness of the electric double layer capacitor is larger than the above range, the whole volume becomes too large, and although the pulse discharge characteristics are improved, the electric capacity may be reduced in proportion to the volume. Furthermore, when the current collector of the electric double layer capacitor is a metal plate and also serves as one of the sealing structures, the structure can be simplified by directly contacting the outer wall of the battery, and the volume can be effectively used. It is preferable because it can also be performed.

When the battery is a prismatic battery, flexibility is not particularly required, but it is preferable that the battery be thin and have a large area, and it is preferable that the battery is in the form of a sheet as described above. Further, in order to obtain an appropriate improvement in pulse discharge characteristics, the thickness of the electric double layer capacitor is preferably in the range of 0.07Y to 0.3Y with respect to the thickness (Y) of the battery. That is, when the thickness of the electric double layer capacitor is in the range of 0.07Y to 0.3Y with respect to the thickness (Y) of the battery, the same shape is maintained without greatly changing the thickness of the battery. Since an electric double layer capacitor having an appropriate capacity can be attached, effective pulse discharge characteristics can be improved, but when the thickness of the electric double layer capacitor is smaller than the above range, the capacity of the electric double layer capacitor becomes insufficient. If the thickness of the electric double layer capacitor is larger than the above range, the overall volume becomes too large and the pulse discharge characteristics are improved, but the volume of the electric double layer capacitor is increased. May have a reduced electrical capacity.

[0012]

Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

Example 1 An electric double layer capacitor shown in FIG. 1 was prepared by using two rectangular aluminum plates having a thickness of 0.25 mm and external dimensions of 32 mm × 46 mm and using them as exterior materials.

The positive electrode 11 has a thickness of 0.3 mm and is made of a rectangular activated carbon fiber having an outer dimension of 28 mm × 42 mm. The negative electrode 12 also has a thickness of 0.3 mm and an outer dimension of 2 mm.
It is composed of a rectangular activated carbon fiber of 8 mm × 42 mm. The separator 13 is made of a polypropylene nonwoven fabric, and is disposed between the positive electrode 1 and the negative electrode 2.

The electrolyte is propylene carbonate in 4-ethylammonium trifluoroborate (Et ₄ N.
BF ₄ ) was dissolved at 1 mol / l.
3 and the like are accommodated in a space surrounded by the positive electrode current collector 14, the negative electrode current collector 15 and the frame 16, and their joint surfaces are sealed with an adhesive so that the electrolyte does not leak out. ing.

Both the current collector plate 14 for the positive electrode and the current collector plate 15 for the negative electrode are made of an aluminum plate having a thickness of 0.25 mm as described above, and the frame 16 is made of polyethylene terephthalate. Is 1.4m
m.

On the other hand, as the battery, a rectangular lithium ion secondary battery having a thickness of 8 mm and an outer dimension of 34 mm × 48 mm was used, and the positive current collector plate 14 of the electric double layer capacitor 1 was used.
The battery and the positive electrode terminal of the battery 2 were connected by a lead body 3 made of nickel, and except for the terminal portion, covered with an exterior material 4 made of polyvinyl chloride to produce a hybrid device shown in FIG.

The battery 2 has a known configuration in which an open circuit voltage is 3.6 V, a theoretical electric capacity is 850 mAh, a lithium cobalt oxide is used as an active material for a positive electrode, and artificial graphite is used as an active material for a negative electrode. Since the thickness (Y) of the battery 2 is 8 mm, the thickness of the electric double layer capacitor 1 (1.4 m) is obtained.
m) is 0.07Y with respect to the thickness of the battery 2 (Y = 8 mm).
０．３0.3 Y (0.56 mm to 2.4 mm). Although not shown in FIG. 2, the negative electrode current collector plate 15 of the electric double layer capacitor 1 and the battery case constituting the negative electrode terminal of the battery 2 are connected by a nickel lead. The hybrid device was fully charged before being used as a power source, and the battery shown in Comparative Example 1 described below was used as a comparative power source, and the pulse discharge characteristics in the mobile phone mode were examined as described later.

Comparative Example 1 Similar to the prismatic lithium-ion secondary battery used in Example 1, the open-circuit voltage was 3.6 V and the theoretical electric capacity was 850 mAh. As a comparative power source for the hybrid device of the above, pulse discharge characteristics in a mobile phone mode were examined.

That is, the hybrid device of Example 1 and the battery of Comparative Example 1 were used as power sources, respectively.
The cell was discharged at a load of 10 ° C. in a mobile phone mode (repeated of 0.5 msec at 1.5 A and 4.0 msec at 0.1 A) to obtain the pulse discharge characteristics shown in FIG.

As shown in FIG. 3, when the discharge is terminated when the minimum voltage of the pulse load becomes 2.75 V, when the hybrid device of the first embodiment is used as a power source, the discharge time is 75 minutes. It can be operated for 75 minutes when used in a mobile phone, whereas when only the battery of Comparative Example 1 is used as a power source, the discharge time is 58 minutes, and it can be seen that only 58 minutes can be operated when used in a mobile phone. .

Example 2 An exterior plate in which a hot melt adhesive was partially laminated on one surface of an aluminum plate having a thickness of 0.1 mm and an outer dimension of 50 mm × 55 mm was used to form a positive electrode, a negative electrode and other contents. An electric double layer capacitor having dimensions of 40 mm × 45 mm was produced. The structure of the electric double layer capacitor in terms of materials such as the positive electrode, the negative electrode, the separator, and the electrolytic solution was the same as that in Example 1, and the hot melt adhesive was a modified polyolefin-based thin sheet. The thing was punched out in a frame shape and used.

The electric double layer capacitor is as shown in FIG. 4, and a separator 13 is provided between the positive electrode 11 and the negative electrode 12.
Is disposed, the aluminum plate serving as the substrate serves as a negative electrode current collector plate 15, a lead body 17 is pulled out from one end of the positive electrode 11, and the entire content is a laminated film of aluminum and plastic. Exterior material 1 consisting of
8 covers.

The electric double layer capacitor 1 does not use a frame as in the first embodiment as a sealing member, but uses a hot melt adhesive to form a thin sealing portion. It was a 2 mm sheet and flexible.

This sheet-shaped electric double layer capacitor is
A 4650 type (cylindrical shape having an outer diameter of 14 mm and a height of 65 mm) was wound around the outer periphery of a lithium ion secondary battery and connected to a lead body to produce a hybrid device shown in FIG. The electric double layer capacitor is wound around the outer periphery of the lithium ion secondary battery by the electric double layer capacitor 1.
This was performed so that the free surface of the negative electrode current collector 15 directly contacted the outer peripheral wall of the battery 2. The outer diameter (X) of the battery 2 is 14 m
m, and the thickness of the electric double layer capacitor 1 (1.2
mm) is 0.0 with respect to the outer diameter of the battery 2 (X = 14 mm).
025X-0.15X (0.035mm-2.1mm)
Is within the range.

Referring to the hybrid device shown in FIG. 5, reference numeral 1 denotes an electric double layer capacitor. The hybrid device is formed by winding the electric double layer capacitor 1 around the outer periphery of the battery 2. First, in the hybrid device, the battery 2 will be described in detail. The positive electrode 21 uses lithium cobalt oxide as an active material,
The negative electrode 22 is made of artificial graphite as an active material. The positive electrode 21 and the negative electrode 22 are spirally wound via a separator 23 made of a microporous polypropylene film, and inserted into the battery case 25 as a spiral electrode body. I have. However,
Prior to the insertion of the spiral electrode body, an insulator 26 made of a polytetrafluoroethylene sheet is disposed in the bottom of the battery case 25, and the polytetrafluoroethylene sheet is arranged along the inner peripheral surface of the battery case 25. An insulator 27 made of ethylene is provided. And this battery case 2
In 5, 1 mol of LiPF ₆ was added to a mixed solvent of ethylene carbonate and ethyl methyl carbonate at a volume ratio of 1: 1.
1 / l dissolved electrolytic solution 24 is injected.

The battery case 25 is made of stainless steel.
The sealing plate 28 is also made of stainless steel, is provided with a gas vent hole 28a at the center thereof, the annular gasket 29 is made of polypropylene, and serves as a negative electrode terminal.
The flexible thin plate 30 is made of titanium, and the heat deformable member 31 is made of polypropylene. The rolled steel terminal plate 32 is provided with a cutting edge 32a and a gas discharge hole 32b, and gas is generated inside the battery to increase the internal pressure of the battery. 30
Is deformed by the cutting blade 32a, the flexible thin plate 30 is broken, and the gas inside the battery is discharged to the gas discharge hole 32b.
From the battery to prevent the battery from being broken under high pressure. And the battery case 25
An annular insulating packing 33 is arranged between the negative electrode 22 and the sealing plate 28, the positive electrode 21 and the sealing plate 28 are electrically connected by an aluminum lead 34, and a lead is connected between the negative electrode 22 and the battery case 25. They are electrically connected by the body 35.

The electric double layer capacitor 1 is wound around the outer periphery of the battery 2 to form a hybrid element. However, FIG. 5 does not show details of the internal structure of the electric double layer capacitor 1, Is indicated by A. However, necessary members are shown for the exterior part, and the negative electrode current collector plate 15 directly contacts the outer peripheral wall of the battery case 25 of the battery 2, and the negative electrode current collector plate 15 and the outer material 1
8 is bonded to the periphery of the electric double layer capacitor 1 with a hot melt adhesive 19 to form a closed structure inside the electric double layer capacitor 1. Then, a lead 17 having one end connected to the positive electrode 11 of the electric double layer capacitor 1 (see FIG. 4)
Is connected to the head of a terminal plate 32 serving as a positive electrode terminal of the battery 2, and the negative electrode current collector plate 15 directly contacts the outer peripheral wall of the battery case 25 constituting the negative electrode terminal of the battery 2. The electric double layer capacitor 1 and the battery 2 can be electrically connected. One end of the lead body 17 reaches the inside of the electric double layer capacitor 1 and is connected to the positive electrode 11. However, FIG. 5 does not show the internal structure of the electric double layer capacitor in detail, so 17 is shown only up to the hot melt adhesive 19 for sealing.

The hybrid device was fully charged before being used as a power source, and the battery shown in Comparative Example 2 described later was used as a comparative power source, and the pulse discharge characteristics in the mobile phone mode were examined as described later.

Comparative Example 2 Using only a lithium ion secondary battery similar to the 14650 type lithium ion secondary battery used in Example 2 as a comparative power source for the hybrid device of Example 2 above,
Pulse discharge characteristics in mobile phone mode were investigated.

That is, the hybrid device of Example 2 and the battery of Comparative Example 2 were used as power sources, respectively, and the mobile phone mode (1.5 A
At a load of 0.5 msec and 0.1 A at a repetition of 4.0 msec) to obtain the pulse discharge characteristics shown in FIG.

As shown in FIG. 6, when the discharge is terminated when the minimum voltage of the pulse load becomes 2.75 V, when the hybrid device of the second embodiment is used as a power source, the discharge time is 60 minutes. While it can operate for 60 minutes when used in a mobile phone, it can be seen that when only the battery of Comparative Example 2 is used as a power source, the discharge time is 40 minutes and only 40 minutes can be used when using a mobile phone.

Example 3 An electric double layer capacitor similar to the electric double layer capacitor shown in FIG.
7 mm and a height of 50 mm) were wound around a lithium thionyl chloride-lithium battery to produce a hybrid device shown in FIGS. Since the outer diameter (X) of the battery 2 is 17 mm and the thickness of the electric double layer capacitor 1 is 1.2 mm as in the case of the second embodiment, the thickness (1.2 mm) of the electric double layer capacitor 1 is Outer diameter of battery 2 (X = 17
mm) to 0.0025X to 0.15X (0.04
25 mm to 2.55 mm).

Referring to the hybrid device shown in FIG. 7, the hybrid device is manufactured by winding the electric double layer capacitor 1 around the outer periphery of the battery 2. The structure of the electric double layer capacitor 1 is the same as that of the second embodiment. Therefore, the description thereof is omitted, and the battery 2 will be described in detail. The positive electrode 41 is formed of a porous carbon molded body, the negative electrode 42 is formed of lithium, and one surface of the negative electrode 42 is formed of a glass fiber nonwoven fabric. The other surface of the negative electrode 42 is opposed to the positive electrode 41 with the separator 43 interposed therebetween.
5 is in close contact with the inner peripheral surface.

The electrolytic solution 44 is formed by dissolving 1.2 mol / l of lithium aluminum tetrachloride in thionyl chloride. Thionyl chloride constituting the electrolytic solution solvent also serves as a positive electrode active material. The positive electrode current collector 46 is made of stainless steel,
The lower end is nailed and inserted into the positive electrode 41, and the upper end is welded to a metal pipe provided on the battery lid 47 to form a positive electrode terminal 50.

The battery cover 47 has a so-called hermetic seal structure, and has an annular stainless steel body 4.
8, a glass layer 49 is formed as an insulating layer on the inner peripheral side, and a metal pipe used as an electrolyte injection port at the time of assembling the battery is provided on the inner peripheral side of the glass layer 49. The metal pipe has a positive electrode current collector. The upper end of the positive electrode terminal 46 is inserted and the upper end of the metal pipe and the positive electrode current collector 46 are welded in this state to form the positive electrode terminal 50.
Is welded to the inner peripheral portion of the open end of the battery to form a sealed structure inside the battery. A bottom insulating material 51 is provided on the bottom inner surface of the battery case 45, an upper insulating material 52 is provided on the positive electrode 41, and an insulating material is provided on the body 48 of the battery cover 47 and the glass layer 49. Resin layer 53 is formed.
The other end of the lead 17 having one end connected to the positive electrode 11 of the electric double layer capacitor 1 is connected to the positive terminal 50 of the battery 2.
And the negative electrode current collecting plate 15 of the electric double layer capacitor 1 is connected to the battery case 45 forming the negative terminal of the battery 2.
The electric double layer capacitor 1 and the battery 2 are electrically connected by being in direct contact with the outer peripheral wall of the electric double layer capacitor.
One end of the lead member 17 reaches the inside of the electric double layer capacitor 1 and is connected to the positive electrode 11. However, FIG. 7 does not show the internal structure of the electric double layer capacitor in detail, so that FIG. As in the case of (1), the lead member 17 is shown only up to the hot melt adhesive 19 for sealing.

Using the above-mentioned hybrid element as a power source and the battery shown in Comparative Example 3 below as a comparative power source, as shown below, after long-term storage at 60 ° C. after partial discharge, discharge at a constant resistance and discharge characteristics Was examined.

COMPARATIVE EXAMPLE 3 Using only a thionyl-lithium chloride battery similar to the ER17 / 50 type thionyl-lithium chloride battery used in Example 3 as a comparative power source for the hybrid device of Example 3 above, The discharge was performed in the same manner as in Example 3, and the discharge characteristics were examined.

That is, the hybrid device of Example 3 and the battery of Comparative Example 3 were used as power sources, respectively.
After storage at 60 ° C. for 12 days after 0% partial discharge, 220
Discharging was performed with a constant resistance of Ω to obtain the discharge characteristics shown in FIG.

As shown in FIG. 9, Example 3 is different from Comparative Example 3
In comparison with, the voltage drop at the start of discharge is small, and the discharge characteristics when stored for a long time after partial discharge can be improved,
It was also found that the method was effective for pulse load use.

[0041]

As described above, according to the present invention,
By using the electric double layer capacitor and the battery as a hybrid element, a power source having excellent pulse discharge characteristics, particularly, a pulse discharge characteristic at a low temperature could be obtained. In addition, there is also an advantage that handling is facilitated by integrating them.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an electric double layer capacitor used in Example 1 with a partial cutout.

FIG. 2 is a schematic perspective view showing the hybrid device of the first embodiment with a partial cutout.

FIG. 3 is a diagram showing pulse discharge characteristics of the hybrid lithium ion battery of Example 1 and a prismatic lithium ion secondary battery of Comparative Example 1 having a configuration similar to that of the prismatic lithium ion secondary battery used for manufacturing the hybrid device.

FIG. 4 is a schematic perspective view showing an electric double-layer capacitor used in Example 2 with a partial cutout.

FIG. 5 is a schematic sectional view showing a hybrid device of Example 2.

FIG. 6 is a diagram showing pulse discharge characteristics of a hybrid device of Example 2 and a 14650 type lithium ion secondary battery of Comparative Example 2 having the same configuration as the 14650 type lithium ion secondary battery used for its production. .

FIG. 7 is a schematic sectional view showing a hybrid device according to a third embodiment.

FIG. 8 is a schematic perspective view showing the hybrid device of the third embodiment with a partial cutout.

FIG. 9 shows the hybrid device of Example 3 and the ER17 / 50 of Comparative Example 3 having the same configuration as the ER17 / 50-type thionyl chloride-lithium battery used for its production.
FIG. 3 is a view showing discharge characteristics of a thionyl chloride-lithium battery.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric double layer capacitor 2 Battery 3 Lead body 4 Exterior material

Claims (7)

[Claims] 1. A hybrid element of an electric double layer capacitor and a battery, wherein the electric double layer capacitor and a battery are combined. 2. A hybrid element of an electric double layer capacitor and a battery, wherein the battery according to claim 1 is a secondary battery. 3. The hybrid element of claim 2, wherein the secondary battery is a lithium ion secondary battery. 4. The hybrid device as claimed in claim 2, wherein the secondary battery is a lithium polymer secondary battery. 5. The electric double layer capacitor is sheet-shaped and has a thickness of 0.0025 with respect to the outer diameter (X) of the cylindrical battery.
5. The hybrid element of an electric double layer capacitor and a battery according to claim 1, wherein the value is in the range of X to 0.15X. 6. The electric double layer capacitor is sheet-shaped and has a thickness of 0.07Y to 0.07Y with respect to the thickness (Y) of the prismatic battery.
3. The method according to claim 1, wherein the distance is within a range of 0.3Y.
A hybrid element of the electric double layer capacitor and the battery according to 2, 3 or 4. 7. The electric double layer capacitor according to claim 1, wherein one surface of the electric double layer capacitor also serves as a current collector, and the one surface is in direct contact with the outer wall of the battery to make an electrical connection. Item 7. A hybrid element of an electric double layer capacitor and a battery according to Item 1, 2, 3, 4, 5, or 6.