JPH04366553A - Sealed nickel-zinc battery - Google Patents

Abstract

PURPOSE:To provide a long-lived and highly reliable nickel-zinc battery by using a nickel hydroxide positive electrode plate containing a lanthanide element. CONSTITUTION:A sintered nickel base plate having a determined porosity is impregnated with a nickel nitrate aqueous solution containing determined amounts of lantern nitrate and cobalt nitrate, and then dipped in a sodium hydroxide aqueous solution. Thereafter, washing with hot water and drying are conducted to form a positive electrode plate. The positive electrode plate and a negative electrode plates are lapped in separators, respectively and then alternately laminated to form an electrode plate group, and a potassium hydroxide aqueous solution saturated with zinc oxide is used as an electrolyte to provide a nickel-zinc battery. Thus, the hydrogen gas generated from the zinc negative electrode plate when charged or let alone is effectively absorbed by the positive electrode plate to extend the life, and reliability is improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed nickel-zinc electrode.

0002

[Background Art and its Problems] In recent years, with the development of electronic equipment, new high-performance batteries are expected to appear. Among these, there is a growing demand for higher performance batteries that use zinc as the negative electrode, such as alkaline manganese batteries and nickel-zinc batteries. In particular, although these batteries have potential as secondary batteries, their short cycle life has made it difficult to put them into practical use. The major technical challenges include the dendrite phenomenon and shape change phenomenon of zinc.

As one means to overcome these problems, attempts have been made to add copper powder or cadmium powder as a conductive material to make the current distribution uniform, thereby alleviating these problems (for example, GS NEWS VOL.4
9, 26 (1990), Japanese Patent Application Publication No. 1-315949)
. Furthermore, an attempt to use a circular or elliptical microporous separator has been proposed (Japanese Unexamined Patent Publication No. 1-42522) in an attempt to improve the life performance of a sealed battery. However, because there was no technical means to absorb the hydrogen gas generated during charging or storage from the zinc negative plate, it was not possible to create a reliable sealed battery like a nickel-cadmium battery.

[0004] Although zinc batteries are expected to have high energy density as described above, they have not yet reached the level of practical use due to insufficient longevity performance.

[0005]

[Means for solving the problems] Nickel according to the present invention
Zinc batteries are characterized by being equipped with a nickel hydroxide positive electrode plate containing lanthanide elements, and the positive electrode plate has the ability to effectively absorb hydrogen gas generated from the zinc negative electrode plate during charging or during storage. It can be used as a reliable sealed battery like a nickel-cadmium battery.

[0006]

EXAMPLES The present invention will be explained below using preferred examples. [Example 1] A sintered nickel substrate with a porosity of 80% was impregnated with a 5M nickel nitrate aqueous solution containing 2 mol% of lanthanum nitrate and 2 mol% of cobalt nitrate at 80°C.
Immerse in 5M aqueous sodium hydroxide solution at 80°C. After that, it was washed with hot water and dried, and the theoretical capacity was 300 mAh.
Two positive electrode plates with dimensions of 0.8 x 14 x 52 (mm) were manufactured.

Next, 80 parts of zinc oxide powder, 20 parts of metal zinc powder, and 0.2 parts of short nylon fibers with a length of 1 mm were added.
Mix parts. Next, 30 parts of propylene glycol is added and mixed to form a paste. Further, 3 parts of a 60% aqueous dispersion solution of polytetrafluoroethylene powder is added and kneaded.

[0008] Thereafter, it was pressed onto a punched copper metal with a thickness of 0.1 mm using a pressure roller, dried at 150°C, and pressed again to make the theoretical capacity of zinc oxide 500 m.
Three negative electrode plates with dimensions of 0.7 x 15 x 52 (mm) were manufactured using Ah.

[0009] Next, this positive electrode plate was wrapped with a separator consisting of one sheet of polyamide nonwoven fabric of 0.12 mm and one sheet of microporous polyethylene membrane of 25 μm thickness, and then heat-sealed. Subsequently, the negative electrode plate was wrapped with a sheet of polyamide nonwoven fabric of 0.12 mm, and then the positive electrode plate and the negative electrode plate were stacked alternately to form an electrode plate group.

[0010] A prismatic nickel-zinc battery according to the present invention uses this electrode plate group, 2.5 ml of an 8.5 M potassium hydroxide aqueous solution saturated with zinc oxide as an electrolyte, and a synthetic resin battery case with a nominal capacity of 500 mAh. (A) was produced. The external dimensions are 67 x 16.5 x 8 (mm), and the battery is equipped with a safety valve that operates at 0.5 Kg/cm2. [Example 2] 85 parts of 5 μm spherical nickel hydroxide powder containing 2 mol% of cobalt hydroxide and 2 mol% of lanthanum hydroxide, 10 parts of metallic cobalt powder, and 5 parts of carbonyl nickel powder are mixed. Next, 40 parts of 0.2% carboxymethyl cellulose is added and mixed to form a paste.

[0011] This paste was filled under reduced pressure into a foamed nickel (manufactured by Sumitomo Electric Industries, Ltd., trade name: Celmet) with a thickness of 1.2 mm, dried at 90°C for 20 minutes, and then pressurized, resulting in a theoretical capacity of 300 mAh. , dimensions are 0.8 x 14 x 52
(mm) two positive electrode plates were manufactured.

Next, 80 parts of zinc oxide powder, 20 parts of metal zinc powder, and 0.2 parts of short fibers of a copolymer of vinyl chloride and acrylonitrile having a length of 1 mm were mixed with 30 parts of propylene glycol to form a paste. Make it. Next, 3 parts of a 60% aqueous dispersion solution of polytetrafluoroethylene powder is added and kneaded. After that, the thickness is 0.1
mm copper punched metal with a pressure roller, dried at 150 °C, and pressed again to form a sheet with a theoretical capacity of zinc oxide of 500 mAh and dimensions of 0.7 × 15 ×
Three 52 (mm) negative electrode plates were manufactured. Next, this positive electrode plate was wrapped in a separator consisting of one sheet of polyamide nonwoven fabric of 0.12 mm and one sheet of microporous polyethylene film of 25 μm thickness, and then heat-sealed. Followed by 0.
After wrapping the negative electrode plate with one sheet of 12 mm polyamide nonwoven fabric, the positive electrode plates and negative electrode plates were stacked alternately to form an electrode plate group.

This electrode plate group and 2.5 ml of an 8.5 M potassium hydroxide aqueous solution saturated with zinc oxide as an electrolyte
A prismatic nickel-zinc battery (B) according to the present invention was manufactured using a synthetic resin battery case with a nominal capacity of 500 mAh. The external dimensions are 67 x 16.5 x 8 (mm), and the battery is equipped with a safety valve that operates at 0.5 Kg/cm2.

A cycle test was conducted in which these batteries were charged at 35° C. and 0.5 C for 6 hours, stored at the same temperature for 2 weeks, and then discharged to 1.40 V at the same current. Figure 1 shows the change in capacity retention rate with the passage of cycles, based on the discharge capacity in the first cycle. For comparison, a conventional battery (C) manufactured in the same manner as Battery (A) in Example 1 except that an impregnating liquid containing no lanthanum nitrate was used is also shown. FIG. 2 shows the change in battery weight loss.

From FIG. 1, it can be seen that batteries (A) and (B) of the present invention
It can be seen that the decrease in capacity of battery (C) is smaller than that of conventional battery (C). Furthermore, from the weight reduction of the battery shown in FIG. 2, it can be said that the battery of the present invention has excellent sealing performance. The reason may be as follows.

Generally, when charging a nickel-zinc battery,
Hydrogen is generated locally from the surface of the copper current collector used as the current collector of the zinc electrode by the reaction shown in equation (1). Further, during storage of the battery, the metal zinc of the zinc electrode corrodes, and hydrogen gas is similarly generated by the reaction of formula (2).

2H2 O+2e− →H2 +2OH−
(1) Zn+2H2 O+2OH- →
H2 +Zn(OH)4 2- (2) Therefore, it can be seen that in the battery of the present invention, hydrogen gas generated from the zinc electrode is absorbed within the battery without being diffused outside the battery system. Probably, the hydrogen gas generated from the negative electrode is expressed by the formula (
It is thought that it was absorbed into the positive electrode active material through the reaction shown in 3).

2NiOOH+H2 →2Ni(OH)2
(3) On the other hand, in the case of conventional batteries, the ability to absorb this hydrogen gas is low, so hydrogen gas generated during charging and during storage is dissipated, resulting in a decrease in electrolyte solution. In particular, if hydrogen is generated while the battery is left after charging, the amount of metallic zinc in the negative electrode decreases, resulting in a decrease in discharge capacity, and subsequent charging overcharges the positive electrode and generates oxygen gas. When hydrogen gas accumulates inside the battery, it becomes difficult for the negative electrode to absorb this oxygen gas, so it is presumed that this oxygen gas is dissipated out of the battery system through the valve, resulting in a large decrease in the electrolyte.

Next, nitrates of cerium, neodymium, samarium, europium, and dysprosium were selected as the lanthanide elements, and a battery was manufactured in the same manner as in Example 1, and the same test as in FIG. 1 was conducted. Ta. Table 1 shows the capacity retention rate and battery weight loss values at the 12th cycle.
are summarized in

[0020]

[Table 1] From the table, it can be seen that the sealed battery of the present invention using a positive electrode plate containing lanthanide elements has much better performance than the conventional battery. As described above, the reason why the sealed battery according to the present invention has excellent performance is presumed to be that the lanthanide element added to the positive electrode has a function of increasing the number of hydrogen absorption sites of Ni00H, which is a charging product of the active material.

[0021] In Example 1, a similar test was conducted on a battery using conventional cellophane as a separator, but the battery using a microporous membrane had better performance.

[0022]

Effects of the Invention As described above, the sealed battery of the present invention contains lanthanide elements in the positive electrode active material, thereby efficiently converting hydrogen gas generated from the negative electrode into the positive electrode active material during charging or while the battery is left standing. Good absorption results in long-life, highly reliable batteries.

[Brief explanation of the drawing]

FIG. 1 is a diagram comparing the capacity retention rate of a sealed battery of the present invention and a conventional battery during charge/discharge cycles.

FIG. 2 is a diagram comparing the amount of weight loss due to charge/discharge cycles between the sealed battery of the present invention and a conventional battery.

Claims (2)

[Claims] 1. A sealed nickel-zinc battery comprising a nickel hydroxide positive electrode plate containing lanthanide elements. 2. A sealed nickel hydroxide positive electrode plate containing lanthanide elements and cobalt hydroxide.
zinc battery.