JP3096464B2 - Nickel-hydrogen alkaline storage battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a nickel-metal hydride alkaline storage battery.

(Prior Art) In recent years, a nickel-hydrogen alkaline storage battery using a hydrogen storage alloy electrode containing a hydrogen storage alloy for a negative electrode and a nickel oxide electrode containing a nickel oxide for a positive electrode has been known as a general alkaline storage battery. -It is possible to obtain 1.5 times or more the energy density compared to cadmium storage batteries, and various types of batteries are being studied as batteries that can support high capacity.

The above-described nickel-hydrogen alkaline storage battery has a structure in which an electrode group in which the hydrogen storage alloy electrode and the nickel oxide electrode are spirally wound with a separator interposed therebetween is housed in an outer can and hermetically sealed. . Conventionally, in the nickel-hydrogen alkaline storage battery, the outer can also serves as a negative electrode terminal, as in a general alkaline storage battery, and the outermost peripheral end of the electrode group is an end of a hydrogen storage alloy electrode that is a negative electrode. In such a manner, a hydrogen storage alloy electrode is brought into contact with the inner wall of the outer can to collect current (Japanese Patent Application Laid-Open Nos.
No. -130053, JP-A-61-99278) are known. By adopting a structure in which the outermost end of the electrode group is the end of the hydrogen-absorbing alloy electrode, the manufacturing process is simplified, current collection is ensured, and the nickel oxide electrode is generated during overcharge. The oxygen gas thus reduced is reduced to water by the hydrogen-absorbing alloy electrode, thereby suppressing a pressure rise inside the battery and stabilizing the battery characteristics. Therefore, by adopting a structure in which the outermost end of the electrode group is the end of the hydrogen storage alloy electrode, the oxygen gas can be efficiently reduced, and the battery characteristics can be further stabilized.

However, the conventional nickel-hydrogen alkaline storage battery has a problem that the internal pressure of the battery greatly increases during overcharge (high-rate charge), a problem that a voltage drop due to polarization during large-current discharge increases, and Since the position of the innermost nickel oxide electrode of the group is not restricted, there is a problem that the swelling of the nickel oxide electrode increases and the utilization rate of the positive electrode active material decreases.

(Problems to be Solved by the Invention) The present invention has been made to solve the conventional problems, and suppresses a rise in internal pressure of a battery, reduces a voltage drop, and improves a utilization rate of a nickel oxide electrode. It is intended to provide a nickel-hydrogen alkaline storage battery having an increased battery capacity.

[Configuration of the Invention] (Means for Solving the Problems) The present invention provides a hydrogen storage alloy electrode including a hydrogen storage alloy,
An electrode group in which a nickel oxide electrode containing nickel oxide is spirally wound via a separator is housed in an outer can, and in a sealed nickel-hydrogen alkaline storage battery, the electrode group is an innermost end thereof. And a structure in which the ends of the hydrogen storage alloy electrode are located at the outermost peripheral ends, respectively.

The hydrogen storage alloy contained in the hydrogen storage alloy electrode is not particularly limited, and can store hydrogen electrochemically generated in an electrolytic solution and can easily release the stored hydrogen during discharge. As long as it is sufficient, LaNi ₅ alloy, MmNi ₅ alloy (Misch metal) or LmNi ₅ alloy (La-enriched Misch metal), and a part of Ni of these alloys are Co, Al, Mn, Fe, Cu, Ti and A multicomponent alloy substituted with at least one selected from the group consisting of Cr is desirable.
When the hydrogen storage alloy electrode contains these hydrogen storage alloys, the battery capacity can be further increased, and the battery characteristics can be further stabilized.

(Operation) According to the present invention, the end of the hydrogen storage alloy electrode is located at the innermost peripheral edge and the outermost peripheral edge of the electrode group housed in the outer can. The hydrogen storage alloy electrode can be opposed to the entire surface. Therefore, oxygen gas generated from the nickel oxide electrode at the time of overcharging is rapidly reduced to water by the facing hydrogen storage alloy electrode, the pressure rise inside the battery can be suppressed, and the nickel oxide electrode can be used efficiently. To be
Since the current density is reduced, the voltage drop due to polarization at the time of large current discharge can be reduced, the battery capacity can be increased, and the positions of all nickel oxide electrodes are regulated by the hydrogen storage alloy electrodes. The nickel oxide electrode can be efficiently used by suppressing swelling of the nickel oxide electrode and preventing a decrease in the utilization rate of the positive electrode active material.

EXAMPLES Hereinafter, the nickel-hydrogen secondary battery of the present invention will be described more specifically in Examples.

Example 1 _{First, LmNi 4.2 Co 0.2 Mn 0.3 Al} 0.3; mechanically particle size of (Lm La enriched misch metal) hydrogen absorbing alloy having a composition represented by
It was pulverized to a size of 74 μm or less and powdered. Subsequently, a paste was prepared by adding PTFE as a binder, CMC and sodium polyacrylate as a viscous agent, and carbon black and water as a conductive agent to the hydrogen storage alloy powder. 95mm ×
It was cut to 39 mm x 0.40 mm to produce a hydrogen storage alloy electrode.

Meanwhile, nickel hydroxide 90 parts by weight and cobalt monoxide 10
A paste is prepared by adding a binder, a viscous agent and water to parts by weight, then the paste is filled into a nickel sintered fiber substrate (95% porosity), dried and rolled, and cut into 63 mm x 39 mm x 0.70 mm. Then, a nickel oxide electrode was produced.

As shown in FIG. 1, a 0.20 mm-thick polyamide nonwoven fabric separator 3 is interposed between the hydrogen-absorbing alloy electrode 1 and the nickel oxide electrode 2 produced by the above-described method. Were spirally wound to form an electrode group. This electrode group is inserted into an AA size space of an acrylic resin container equipped with a pressure detector, and a KOH7 standard and LiOH1 standard electrolyte solution is filled in this space.
2.4 ml was injected, sealed, and a test cell as shown in FIG. 3 was assembled. That is, this test cell includes a battery case including a case main body 11 and a cap 12 made of an acrylic resin.
At the center of the case main body 11, a space 13 having the same inner diameter and height as the metal container of the AA size battery is formed.In the space 13, an electrode group 14 is housed. Is housed. The cap 12 serves as a sealing plate, and has a pressure detector 15 attached so that the internal pressure of the battery can be detected. The case body
On the cap 11, the cap 12 is a rubber sheet 16 and an O-ring.
It is airtightly fixed by bolts 18 and nuts 19 via 17. The negative electrode lead 20 from the hydrogen storage alloy electrode and the positive electrode lead 21 from the nickel oxide electrode
And the O-ring 17.

Comparative Example 1 As shown in FIG. 2, the thickness was between the hydrogen storage alloy electrode 1 'and the nickel oxide electrode 2' produced in the same manner as in Example 1.
A 0.20 mm polyamide nonwoven fabric separator 3 ′ is interposed and spirally wound so that the end of the nickel oxide electrode 2 ′ is the innermost end and the hydrogen storage alloy electrode 1 ′ is the outermost end. A test cell similar to that of Example 1 was assembled except that a group was prepared.

After the obtained test cell of Example 1 (nominal capacity of 1100 mAh) and the test cell of Comparative Example 1 (nominal capacity of 950 mAh) were allowed to stand at a temperature of 45 ° C. for 24 hours, they were initially charged to 150% of the battery capacity (current value). , Example 1; 110 mA, Comparative Example 1; 95 mA).

After first charge, charge up to 150% of battery capacity at 1 CmA, 1 CmA
, And a cycle characteristic test was performed. However, a rest time of 30 minutes was taken between charging and discharging and between discharging and charging. In such a cycle characteristic test, the battery voltage was 1.
Table 1 below shows the discharge capacity before reaching 0 V and the discharge capacity when the battery voltage reached 1.0 V when a large current discharge of 5 CmA was performed at the 30th cycle. Also, at the 30th cycle
FIG. 5 shows a change in the battery voltage with respect to the discharge capacity when a large current discharge of 5 CmA is performed. Table 1 also shows the number of cycles (cycle life) when the internal pressure of the battery reached 20 kg / cm ² in the cycle characteristic test.

As is clear from Table 1 and FIG. 5, the test cell of Example 1 has a longer cycle life than the test cell of Comparative Example 1, and has a high operating voltage (high polarization) with respect to the large current discharge characteristic of 5 CmA discharge. Was large) and the discharge capacity was large and good.

FIG. 4 shows the behavior of the battery internal pressure with respect to the charge capacity at the time of charging in the 50th cycle in the cycle characteristic test. As is clear from FIG. 4, the test cell of Example 1 had a battery internal pressure of only about 6 kg / cm ² despite the high rate of charge of 1 CmA, and the oxygen gas reduction reaction was rapid. I knew it was going on. On the other hand, Comparative Example 1
Test cell has a battery internal pressure of 13kg at 1CmA high rate charging
/ cm ² , which indicates that the reduction reaction of oxygen gas is not rapidly performed.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to suppress a rise in internal pressure of a battery during overcharge, reduce a voltage drop due to polarization during large current discharge, and achieve a high capacity of the battery. It is possible to provide a nickel-metal hydride alkaline storage battery which can sufficiently cope with the conversion.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an electrode group of Example 1, FIG. 2 is a sectional view showing an electrode group of Comparative Example 1, FIG. 3 is a sectional view showing a test cell used in the example, and FIG. FIG. 5 is a characteristic diagram showing a change in battery internal pressure with respect to a charge capacity at the time of charging in a 50th cycle in a cycle characteristic test, and FIG. 5 is a characteristic diagram showing a change in battery voltage with respect to a discharge capacity in a large current discharge test. 1 ... hydrogen storage alloy electrode, 2 ... nickel oxide electrode,
3 ... separator, 11 ... case body, 12 ... cap, 14 ... electrode group, 15 ... pressure detector.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hirotaka Hayashida 1 Toshiba Research Institute, Komukai, Kawasaki City, Kanagawa Prefecture (72) Inventor Hiroyuki Takahashi 3-4-10 Minamishinagawa, Shinagawa-ku, Tokyo No. Toshiba Battery Co., Ltd. (72) Inventor Ichiro Saruwatari 3-4-10 Minamishinagawa, Shinagawa-ku, Tokyo Toshiba Battery Co., Ltd. (72) Inventor Hiroyuki Hasebe 1 Komukai Toshiba-cho, Koyuki-ku, Kawasaki-shi, Kanagawa Prefecture Address Toshiba Research Institute, Inc. (58) Field surveyed (Int. Cl. ⁷ , DB name) H01M 10/28-10/30

Claims (4)

(57) [Claims] 1. A hydrogen storage alloy electrode including a hydrogen storage alloy,
An electrode group in which a nickel oxide electrode containing nickel oxide is spirally wound with a separator interposed therebetween is housed in an outer can, and in a sealed nickel-hydrogen alkaline storage battery, the electrode group is an innermost end thereof. And a structure in which ends of the hydrogen storage alloy electrode are located at outermost peripheral ends, respectively. 2. The nickel-hydrogen alkaline storage battery according to claim 1, wherein said hydrogen storage alloy electrode is of a paste type. 3. The hydrogen storage alloy is a LaNi ₅ alloy, an MmNi ₅ alloy (where Mm represents a misch metal), an LmNi ₅ alloy (where Lm represents a La-enriched misch metal), and the LaNi ₅ alloy. ₅ alloy, Ni of the MmNi ₅ alloy and the LmNi ₅ alloy
2. A nickel-hydrogen alkaline storage battery according to claim 1, wherein the nickel-hydrogen alkaline storage battery is a multi-component alloy in which a part of is replaced by at least one element selected from Co, Al, Mn, Fe, Cu, Ti and Cr. 4. The nickel-hydrogen alkaline storage battery according to claim 1, wherein said nickel oxide electrode is of a paste type.