JPH10241664A - Electrode structure of battery using thin electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode structure of a battery using a thin electrode, capable of reducing a temperature difference inside the battery. SOLUTION: An electrode 10 is fixed to a battery case 14, via an insulation member 16. For the electrode 10, a cavity path opened to the outside of a battery case at both ends is formed. For this electrode 10, a battery is formed by winding a positive and a negative electrode sheet via a separator. The heat generated during battery charging and discharging is discharged from the surface of the battery case 14 and discharged from a cavity path 12 of the electrode 1, and a temperature difference inside the battery can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an improvement in the electrode structure of a battery using a thin electrode.

[0002]

2. Description of the Related Art Heretofore, batteries using thin electrodes as a positive electrode and a negative electrode such as a lithium secondary battery have been known. These batteries generate heat during charging and discharging, and thus have a problem that the electrolyte or the electrodes are deteriorated due to high temperatures.

[0003] Therefore, in the batteries using these conventional thin electrodes, for example, T920 reported by the Central Research Institute of Electric Power Industry.
84, etc., measures such as attaching fins to the outer surface of the battery have been taken. Thereby, the contact area with the outside air increases, and the heat radiation of the battery is improved.

[0004]

However, in the above-mentioned conventional cooling method using fins or the like, from the outside of the battery case,
Since the cooling is performed via the battery case, the temperature becomes higher toward the center of the battery as compared to the vicinity of the wall of the battery case. For this reason, there has been a problem that a temperature difference occurs inside the battery, and the internal resistance varies. This is because lithium ions are easily intercalated in the electrode active material and the electric resistance of the electrolyte depends on the temperature. When the internal resistance of the battery varies, the operation of the battery becomes uneven, the capacity is reduced, and local overcharging and overdischarging are likely to occur. In particular, in the case of a battery used in an electric vehicle or the like which requires a large current to flow, the above-described problem is further increased because the amount of generated heat increases.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide an electrode structure of a battery using a thin electrode capable of reducing a temperature difference inside the battery.

[0006]

In order to achieve the above object, the present invention relates to an electrode structure for a battery using a thin electrode in which positive and negative thin electrodes are attached and fixed to a battery case via an insulating member. In addition, it is characterized in that both ends have a hollow path opened to the outside of the battery case.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a configuration diagram of an electrode structure of a battery using a thin electrode according to the present invention. In FIG. 1, the electrode 10 has a hollow path 12 and has a cylindrical shape. This electrode 10 is fixed to a battery case 14 via an insulating member 16. As shown in FIG. 1, both ends of the hollow path 12 are open to the outside of the battery case.
Therefore, the hollow passage 12 penetrating the electrode 10 in the longitudinal direction thereof
Can be in contact with the outside air.

FIG. 2 is an explanatory view showing a case where a thin electrode is attached to the electrode structure shown in FIG. In FIG. 2, the electrode 10 on the positive electrode side has LiCoO ₂ on an aluminum foil.
Is applied, and the positive electrode sheet 18 constituting the thin electrode is fixed by the welding portion 20. Further, on the negative electrode 10, natural graphite is applied on a copper foil, and a negative electrode sheet 22 constituting a thin electrode is fixed by a welded portion 20. The negative electrode sheet 22 is covered with a bag-shaped separator 24 so as not to short-circuit with the positive electrode 10 and the positive electrode sheet 18.

The above-described positive electrode sheet 18 and negative electrode sheet 22 are laminated with a separator 24 interposed therebetween, and are wound around the positive and negative electrodes 10. This is shown in FIG. Note that the illustration of the separator 24 is omitted in FIG. As shown in FIG. 3, the positive electrode sheet 18 and the negative electrode sheet 22 are wound around two positive and negative electrodes and are wound in an elliptical shape. This facilitates storage in the rectangular battery case 14 and contributes to an improvement in the volume density of the battery capacity.

Since the above-described positive electrode sheet 18 and negative electrode sheet 22 are wound around the electrode 10 having the hollow passage 12, heat generated from each of the electrode sheets 18, 22 during charging and discharging of the battery. Is dissipated from the surface of the battery case 14 and also from the hollow path of the electrode 10. In this case, each of the electrode sheets 18 and 22 is
Are connected to each other via the welding portion 20, the heat generated in each of the electrode sheets 18 and 22 is directly radiated from the electrode 10, and the radiation efficiency can be further improved. As described above, since the heat generated in the central portion of the battery is radiated through the hollow passage 12, the temperature difference inside the battery can be reduced. Further, if a cooling medium such as air is forced to pass through the hollow passage 12 of the electrode 10, the heat radiation characteristics can be further improved.

The hollow passage 12 is not necessarily provided with the electrode 1
Although it is not necessary to form it at 0, if it is formed at a portion other than the electrode 10, an extra volume is required, which is disadvantageous in that the volume density of the battery capacity is reduced. In this case, each of the electrode sheets 18 and 22 is
And the heat is not directly radiated from the hollow path 12, so that the heat radiation characteristics are lower than in the above example.

Further, although the shape of the electrode 10 is shown as an example of a cylindrical shape having the hollow passage 12, it is not necessarily limited to the cylindrical shape, but may be a square rod shape. The cross-sectional shape of the hollow path 12 is not necessarily limited to a circle, but may be, for example, a square.

The above description assumes a lithium secondary battery, but the present invention is not limited to this.
It can be widely applied to batteries using thin electrodes such as i-H batteries.

Hereinafter, examples of the electrode structure of the battery using the thin electrode according to the present invention will be described together with comparative examples.

Embodiment 1 Reversible desorption of lithium ions
Active materials that can be inserted, such as LiCoO ₂ , LiNi
O ₂ , LiMn ₂ O _4, etc., and a conductive material such as graphite or carbon black are mixed in an NMP (N-methyl-2-pyrrolidone) solution in which a fluororesin such as PVDF as a binder is dissolved. And kneaded to make a paste.
This paste is applied on an aluminum current collector foil, and then heated and dried and pressed to obtain a positive electrode sheet 18.

Similarly, Li ions are inserted reversibly.
A carbon material such as a desorbable active material, for example, natural graphite, is mixed and kneaded in the binder solution to form a paste. This paste is applied on a copper current collector foil, and then heated and pressed to obtain a negative electrode sheet 22.

Battery case upper lid (width 100 x depth 2)
In 5), a round bar (4 mm in diameter) as the electrode 10 is fixed at a position 15 mm from the center of the lid. At the center of this round bar, a cavity (cavity diameter 2 mm) is formed as the hollow path 12. The round bar is insulated from the case by a resin (such as PTFE) as the insulating member 16. As the material of the round bar, it is necessary to have low electric resistance and electrochemical stability.
Nickel, stainless steel, and copper, nickel, stainless steel, and the like can be used for the negative electrode.

One end of each of the positive and negative electrode sheets 18 and 22 is fixed to the round bar by laser welding or the like. The negative electrode sheet 22 is
It is sandwiched between two pieces of porous polyethylene film, and is turned around the round bar of the negative electrode. Thereby, the positive electrode sheet 18
Can be prevented from contacting the round bar of the negative electrode. Thereafter, the positive and negative electrode sheets 18 and 22 are wound in an elliptical shape around two round bars of the positive and negative electrodes.

The wound product is stored in the battery case 14 (width 100 × depth 25 × height 90), and the lid is sealed by laser welding. In this case, the two round bars are completely insulated from the battery case 14.

Finally, an electrolyte is injected to complete the battery. The discharge capacity of the battery thus manufactured was 8 Ah.

Comparative example. The electrode manufactured in the same manner as in the above embodiment is cut into strips, and the positive electrode, the separator, and the negative electrode are superposed in this order, and are housed in a battery case to constitute a battery. At this time, the discharge capacity of the battery was 8 Ah.

Next, the batteries of the above Examples and Comparative Examples were heated at 20 ° C.
The battery temperature was measured by providing a thermocouple outside the battery case 14 when the battery was charged and discharged at a constant current of 1 hour rate in the constant temperature bath set as described above. As a result, the temperature at the end of discharge rose to 30 ° C. in the comparative example, but rose only to 26 ° C. in the example.

Further, the wind speed is 5 m / sec from the bottom of the battery.
When cooling at room temperature by flowing air at
C., but only increased to 23.degree. C. in the example. This is considered to be because, in the case of the embodiment, the cooling air flows through the cavity of the round bar, and heat radiation from the inside of the battery is promoted.

It has been found that the provision of the cooling cavity in the battery improves the heat radiation and suppresses the temperature rise during charging and discharging. In particular, in the present invention, it is considered that the heat dissipation through the current collector foil is promoted by connecting the round bar as the electrode 10 to the current collector foil, and the heat dissipation is further improved.

[0026]

As described above, according to the present invention,
By the hollow passage formed in the electrode, the heat generated inside the battery case can be efficiently released to the outside, and the temperature difference in the battery can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an electrode structure of a battery using a thin electrode according to the present invention.

FIG. 2 is an explanatory diagram of a case where a positive electrode and a negative electrode sheet are attached using the electrode structure shown in FIG. 1;

FIG. 3 is an explanatory diagram of a case where the positive electrode sheet and the negative electrode sheet shown in FIG. 2 are wound around electrodes.

[Explanation of symbols]

10 electrode, 12 hollow path, 14 battery case, 16
Insulation member, 18 positive electrode sheet, 20 weld, 22
Negative electrode sheet, 24 separator.

Claims (1)

[Claims] An electrode structure for a battery using a thin electrode, to which a thin positive and negative electrode is attached and fixed to a battery case via an insulating member, the hollow structure having hollow paths open at both ends to the outside of the battery case. An electrode structure for a battery using a thin electrode.