JPH05290829A - Sealed alkaline storage battery - Google Patents

Abstract

PURPOSE:To provide a sealed alkaline storage battery capable of obtaining large discharge capacity with charge-receiving property improved. CONSTITUTION:An aluminum-made terminal, applied with nickel plating or copper plating, is used as a negative electrode terminal 5. Large discharge capacity can be provided by improving the charge receiving property of the battery by discharging heat, generated when oxygen generated from a positive electrode as sub-reaction at the time of charging is returned to water on a negative electrode outside the battery quickly to restrain the temperature rise of the battery.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed alkaline storage battery, and more particularly to a large sealed alkaline storage battery using nickel hydroxide as a positive electrode active material having improved charging characteristics.

[0002]

2. Description of the Related Art In recent years, attention has been paid to sealed nickel-metal hydride storage batteries, nickel-cadmium storage batteries, and nickel-zinc storage batteries that use nickel hydroxide for the positive electrode, a hydrogen storage alloy for the negative electrode, and an alkaline aqueous solution for the electrolyte, and can achieve high energy density. ing. Nickel, which has good electric conductivity, has been used for the leads and terminals of the positive and negative electrodes of these batteries.

The charging mechanism at the positive electrode of this battery is represented by the formula (1)
Proceed like. The discharge reaction is the opposite. e ^- is an electron.

Ni (OH) ₂ + OH ⁻ = NiOOH + H ₂ O + e ⁻ (1) However, not only the above reaction but also the side reaction formula (2) at the time of charging.
Happens.

4OH ⁻ = 2H ₂ O + O ₂ + 4e ⁻ (2) Therefore, with respect to the side reaction of the formula (2) at the positive electrode, the oxygen gas generated in the sealed nickel-metal hydride storage battery is guided to the negative electrode to obtain the formula ( A method of using water as in 3) is used, and O ₂ + 4MH = M + 22H ₂ O (3) The airtightness is maintained. Here, M represents a hydrogen storage alloy, and MH represents a hydrogen storage alloy that has stored hydrogen.

The side reaction represented by the formula (2) occurs more predominantly as compared with the formula (1) which is a charge / discharge reaction of the positive electrode as the temperature rises, and at a high temperature, for example, 45 ° C., 150% of the positive electrode filling capacity is obtained. Even if the battery is charged with this amount of electricity, only about 50% of the positive electrode is charged.

[0007]

In the sealed alkaline storage battery, the reaction of the formula (3) is used for sealing, so the reaction heat of the formula (3) is generated in the battery and the battery temperature rises. In the case of a battery having a capacity of about 10 Ah, the temperature rise of the battery is relatively small due to the heat radiation effect from the battery case and the nickel terminal when the battery is charged for 10 hours. However, 25A
In a battery having a capacity of h or more, heat generation becomes more remarkable than heat radiation. Even with a battery having a capacity of 10 Ah, heat generation is remarkable at high rate charging.

Due to this heat generation, the battery temperature increased, the charge acceptance of the positive electrode decreased, and a sufficient discharge capacity could not be obtained.

The present invention solves such a problem, and provides a sealed alkaline storage battery in which charge acceptance at a high temperature is improved and a large discharge capacity is obtained by changing the material of the negative electrode lead or terminal. The purpose is to

[0010]

To achieve this object, the sealed alkaline storage battery of the present invention comprises a chargeable / dischargeable negative electrode,
It comprises a positive electrode made of nickel hydroxide, and an aluminum negative electrode terminal plated with nickel or copper by using an alkaline aqueous solution for disassembly.

[0011]

In the sealed alkaline storage battery, oxygen generated from the positive electrode is returned to water by the reaction of formula (3). The heat of reaction at this time raises the temperature. As is clear from the formula (3), the place where the reaction occurs is on the negative electrode. Therefore, heat is also generated on the negative electrode and transmitted to the positive electrode through the electrolytic solution and the separator. The transferred heat raises the temperature of the positive electrode, and further oxygen is easily generated. The present invention intends to improve the charge acceptability of a battery by releasing the heat generated on the negative electrode to the outside of the battery as quickly as possible and suppressing the temperature rise of the positive electrode to suppress oxygen generation from the positive electrode. Is.

Therefore, in order to quickly release the heat generated on the negative electrode to the outside of the battery, it is conceivable to use aluminum having good thermal conductivity for the leads and terminals of the negative electrode. However, aluminum cannot be used as it is because it causes a chemical reaction with an alkaline aqueous solution and dissolves. Copper-plated or nickel-plated was used to obtain a terminal having good thermal conductivity and not reacting with an alkaline aqueous solution.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sealed alkaline battery according to an embodiment of the present invention will be described below with reference to the drawings.

Powders in which nickel hydroxide, metallic cobalt and cobalt hydroxide were weighed at a weight ratio of 100: 7: 5 were mixed well, and then 20 g of the mixed powder was added with water to form a paste. This paste is filled into nickel foam with a width of 60 mm, a length of 81 mm, and a weight of 3.1 g, and after drying, the thickness is 1.74 mm.
It was compressed into a positive electrode plate. A nickel plate as a lead was spot-welded to the corner of the positive electrode plate. Metallic cobalt contributes to ensuring the discharge reserve, and cobalt hydroxide contributes to improving the charging efficiency at 20 ° C.

At this time, the theoretical capacity of one positive electrode plate is 5.05.
It is Ah. Five positive electrode plates were used for the test battery.

A hydrogen storage alloy was used as the negative electrode. As hydrogen storage alloy, misch metal with 10% lanthanum content (M
Using MmNi _3.55 Mn _0.4 Al _0.3 Co _0.75 with m), and a paste by adding water in the same manner as in the alloy 19.4 g. This paste is filled into nickel foam with a width of 60 mm, a length of 81 mm, and a weight of 3.1 g, and after drying, the thickness is 1.20 mm.
It was compressed into a negative electrode plate. A copper plate having a width of 20 mm and a thickness of 0.2 mm having good thermal conductivity as a lead was spot-welded to a corner of the negative electrode plate. At this time, the theoretical capacity of one negative electrode plate is 5.63 Ah.
Is. Six negative plates were used for the test battery.

As shown in FIG. 1, the negative electrode 2 and the positive electrode 3 were arranged in this order so that the negative electrode 2 was placed outside through the sulfonated polypropylene nonwoven fabric separator 1. Negative electrode 2
The copper lead 4 was spot-welded to the aluminum negative electrode terminal 5 plated with copper to a thickness of 0.1 mm, and the nickel lead 9 of the positive electrode 3 to the nickel positive electrode terminal (not shown). If the plating thickness was 0.05 mm or more, the reaction with the alkaline aqueous solution was hindered.

These electrode plates were placed in a case 6 of 3 mm thick, made of allylnitrile-styrene resin, which had a length of 108 mm, a width of 69 mm, and a width of 18 mm. 54 cc of an aqueous potassium hydroxide solution having a specific gravity of 1.3 was added as an electrolytic solution.

A sealing plate 8 made of allylonitrile-styrene resin, to which a safety valve 7 operating at 2 atmospheres was attached, was attached to a case 6 with an epoxy resin. After that, the positive electrode terminal and the negative electrode terminal 5 are press-contacted and fixed to the sealing plate 8 via an O-ring,
It was a sealed battery. This battery is designated as A. Further, a battery having substantially the same configuration as the above, but using a copper plate for the negative electrode lead 4 and an aluminum terminal with a nickel plating of 0.1 mm as the negative electrode terminal 5, is designated as B. As a comparative example, a battery using a copper plate for the negative electrode lead 4 and a nickel negative electrode terminal 5 is C. As a conventional example, a battery using a negative electrode lead 4 and a negative electrode terminal 5 made of nickel is designated as D. The cells A to D have the same positive electrode theoretical fill capacity.

The batteries A to D were stored at 20 ° C. for 3 hours.
After charging at 45 A for 4.5 hours, a charging / discharging cycle of discharging at a 5-hour rate of 5.06 A until the terminal voltage became 1 V was repeated.

The discharge curve at the 10th cycle is shown in FIG.
As a result, the batteries A and B of the examples have a large discharge capacity,
Charge acceptance is good.

[0022]

As is apparent from the above description of the examples, according to the sealed alkaline storage battery of the present invention, charge acceptability is improved and a large discharge capacity can be obtained, which has great industrial significance. is there.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of the present invention and a conventional sealed alkaline storage battery.

FIG. 2 is a graph showing discharge characteristics at the 10th cycle of the present invention, comparative examples, and conventional sealed alkaline storage batteries.

[Explanation of symbols]

 1 separator 2 negative electrode 3 positive electrode 4 negative electrode lead 5 negative electrode terminal

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Katsunori Komori 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Yoshinori Toyokuchi 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. A hermetically sealed structure comprising a chargeable / dischargeable negative electrode facing each other via a separator, a positive electrode made of nickel hydroxide, and an aluminum negative electrode terminal mainly composed of an alkaline electrolyte and plated with nickel or copper. Type alkaline storage battery.