JP2563241B2 - Zinc alkaline battery - Google Patents

Description

TECHNICAL FIELD The present invention relates to a zinc-alkaline battery using zinc as a negative electrode main active material and an alkaline aqueous solution as an electrolytic solution, and suppressing an increase in battery internal pressure due to hydrogen gas generated in the battery. It provides the means to do.

2. Description of the Related Art In order to suppress the corrosion reaction of the zinc negative electrode of a zinc-alkaline battery due to the electrolytic solution and to prevent self-depletion of zinc and hydrogen gas generation during battery storage, about 5-10% by weight of mercury is added to zinc. It is added to form an amalgam and used as a negative electrode, which is currently used as a general method. As a result, the internal pressure of the battery is prevented from rising due to storage, the liquid leakage resistance and the storability are secured, and the battery is prevailing as a practical battery that does not expand or burst and has little performance degradation. However, in recent years, social needs for low pollution have increased, and research and development have been conducted to reduce the amount of mercury used and to secure the above-mentioned practical performance without using mercury. Even if the reduction is possible to some extent, there is currently no means that can essentially solve the problem.

Problems to be Solved by the Invention For example, a technique using a corrosion-resistant zinc alloy in which lead, indium, gallium, etc. are added to zinc has been studied, and a technique capable of reducing mercury to about 1 to 3% has been studied. It is considered extremely difficult to secure sufficient corrosion resistance of unused negative electrode zinc. Therefore, as another proposal, a method is considered in which hydrogen gas generated in the battery is stored and fixed by a hydrogen storage alloy incorporated in the battery to prevent the internal pressure of the battery from rising.
However, under the present circumstances, there is no specific and appropriate method for effectively incorporating the hydrogen storage alloy, and without sacrificing the effective internal volume occupied by the power generation element in the battery.

The present invention suppresses the increase in the internal pressure of the battery due to the hydrogen gas generated in the battery, and the deterioration of the discharge reaction, so that not only the hydrogen gas in the vacant chamber of the battery but also the hydrogen gas present in the negative electrode or the electrolytic solution. It also provides a low-pollution battery with comprehensive practical performance by storing and fixing it in a hydrogen storage alloy.

Means for Solving the Problems The present invention is characterized in that, in an alkaline manganese battery having a low mercury addition amount, hydrogen is occluded at a relatively low pressure, and microcapsules filled with an inexpensive specific hydrogen occluding alloy are added. To do.

Action Conventionally, what was proposed as a method of incorporating a hydrogen storage alloy into a battery was to focus on preventing the rise of the internal pressure of the battery by storing the hydrogen gas accumulated in the empty space of the battery. In addition, in the present invention, by removing the hydrogen gas existing in the negative electrode or the electrolytic solution by absorbing it in the hydrogen storage alloy, these hydrogen gas eliminate the problem of covering the active surface of the negative electrode and inhibiting the discharge reaction. In addition to preventing leakage and swelling during storage, this also minimizes the deterioration of discharge performance and the amount of mercury used for corrosion protection of the negative electrode is not sufficient, and some hydrogen gas may be generated. This is a low-pollution battery that can exhibit overall practical performance even if it occurs inside the battery. That is, among hydrogen storage alloys that store hydrogen at a relatively low pressure, inexpensive ZrMn _α (0 <α <3.
5), ZrV _β (0 <β <3.5), Ti _{1- γ} Zr _γ M (0 <γ <
1, M = Cr, V, Co, Mn, Ni, Fe, Cu) and CaNi _δ (3.5 <δ
At least one of <6.0) is pulverized and coated with a hydrogen gas permeable thin film of an alkali-resistant resin such as nylon, polyethylene or polypropylene from microcapsules of zinc or zinc alloy powder or a powder of these. When mixed in the negative electrode active material, the hydrogen gas is generated by a corrosion reaction between the negative electrode active material and the alkaline electrolyte during battery storage and adheres to the surface of the negative electrode active material, or hydrogen gas existing as bubbles in the electrolyte. Is stored and fixed in a hydrogen storage alloy, the above-mentioned hydrogen gas that interferes with the discharge reaction is removed, and a normal discharge reaction is performed to minimize deterioration of the battery performance due to storage. When the amount of hydrogen gas generated from the negative electrode increases, the hydrogen gas not only stays in the vicinity of the negative electrode or in the electrolytic solution as described above, but also accumulates in the empty space of the battery to increase the internal pressure of the battery, causing leakage or rupture, or In such a case, it is necessary to mix the microcapsules in the negative electrode and further dispose the above-mentioned microencapsulated hydrogen storage alloy in the vacant space of the battery. By combining the method of wrapping the hydrogen storage alloy and arranging it in the vacant chamber by the method as shown in the examples later,
It is sufficient to prevent the internal pressure from rising by allowing the alloy to occlude hydrogen gas in the vacant chamber.

Example FIG. 1 is a sectional view of a calcarimanganese dry battery to which the present invention is applied.

In the figure, 1 is a metal outer can, 2 is a positive electrode insulating ring, 3 is a negative electrode insulating ring, 4 is an insulating heat-shrinkable tube, 5 is a metallic positive electrode terminal, 6 is a metallic negative electrode terminal, and 7 is iron. A nickel-plated positive electrode case, 8 is a positive electrode positively formed by mixing manganese dioxide with graphite, and 9 is a separator made of polypropylene non-woven fabric. 10 is a gas phase expressed as "vacant space" in the description of the present invention, 11
Is a polypropylene sealing plate, the recess 11 'of this sealing plate.
A microporous tube 13 made of a fluororesin filled with hydrogen-absorbing alloy powder 12 is attached to the inside, and it has a mechanism for storing hydrogen gas accumulated in the vacant chamber 10 and preventing an increase in internal pressure.

14 is a bottom plate made of cellulose, 15 is about 10% of the electrolyte solution of the aqueous solution of causticari gelated with carboxymethyl cellulose.
Zinc alloy powder 16 having an average particle size of 0μ, and a hydrogen-absorbing alloy powder crushed to 10 to 30μ with an average particle size of nylon thin film, about 50μ microcapsules 17 are mixed and dispersed in a gel form. The zinc alloy used in the zinc negative electrode was 0.05% by weight of lead, indium, and gallium, each of which had relatively good corrosion resistance. 18 is a brass negative electrode current collector. In order to study the effect of the present invention, various AA batteries were experimentally manufactured. The hydrogen storage alloys used were all ZrMn ₂ crushed in an argon atmosphere, and the zinc alloys of the negative electrode were taken into the experiment as those not subjected to denaturation treatment. Prototypes that did not contain microcapsules and were equipped with the hydrogen storage alloy 12 only in the vacant chamber, or those that did not contain these alloys at all in the battery were manufactured. The configurations of these prototype batteries were the same as those shown in the figures, except for the contents described above and the trial production contents of Table 1 unless otherwise specified. Table 1 shows the details of the prototype and the test results after storage.

All the test results in Table 1 are the results after storage at 60 ° C for 1 month, and evaluate continuous discharge performance at 20 ° C and 10Ω, leakage resistance, and expansion degree.

As can be seen from Table 1, a is added with a small amount of mercury for suppressing the corrosion of the negative electrode, but the corrosion cannot be completely suppressed,
Since it does not contain hydrogen storage alloy at all, the internal pressure of the battery rises,
Liquid leakage and expansion are remarkable, and the discharge performance is also significantly reduced. Unlike in the case of a, b has a large amount of hydrogen gas generated because the negative electrode has not been subjected to a hydrogenation treatment, but since the vacant chamber contains a large amount of hydrogen storage alloy, it causes a rise in the internal pressure of the battery. The gas is occluded to prevent the internal pressure from rising, and expansion and leakage are stopped. However, since the hydrogen gas stays in the negative electrode and the electrolytic solution, the discharge performance is worse than that of the examples c and d, and the practical performance is less than c and d. c, d
Has all these problems solved and shows excellent practical performance. In the case of c, a large amount of hydrogen gas is generated from the negative electrode, so the problem can be solved by using a hydrogen storage alloy in both the negative electrode and the vacant space. In the case of d, some mercury gas is added to the hydrogen gas to some extent. Since the generation is suppressed, only the hydrogen storage alloy in the negative electrode fulfills a sufficient function. The difference in these effects is obvious for the reasons described above.

EFFECTS OF THE INVENTION As described above, the present invention is an extremely effective means for obtaining a zinc alkaline battery with low pollution and excellent practical performance.

[Brief description of drawings]

The drawing is a cross-sectional view of a battery according to an embodiment of the present invention. 7 ... Positive electrode case, 8 ... Positive electrode, 15 ... Zinc negative electrode, 17 ...
… Microcapsules filled with hydrogen storage alloy.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Koji Takada 1006 Kadoma, Kadoma, Kadoma City, Matsushita Electric Industrial Co., Ltd. (72) Akira Miura 1006 Kadoma, Kadoma, Matsuda Electric Co., Ltd. (56) References JP-A-51-13934 (JP, A)

Claims (1)

(57) [Claims] 1. A zinc-alkaline battery in which manganese dioxide is used as the main active material of the positive electrode, zinc is used as the main active material of the negative electrode, an alkaline aqueous solution is used as the electrolytic solution, and the addition amount of mercury is 0.5% by weight or less based on zinc. ZrMn _α (0 <α <3.
5), ZrV _β (0 <β <3.5), Ti _{1- γ} Zr _γ M (0 <γ <
1, M = Cr, V, Co, Mn, Ni, Fe, Cu) and CaNi _δ (3.5 <δ
A zinc-alkaline battery, wherein microcapsules filled with at least one hydrogen storage alloy of <6.0) are added at least in the negative electrode.