JPH0629042A - Square metal hydride storage battery - Google Patents

Abstract

PURPOSE:To prevent a negative electrode plate from firing by forming each group of electrode plates consisting in a laminate of positive electrode plates and negative electrode plates composed majorly of a hydrogen storage alloy with separators interposed, accommodating the electrode plate group in a battery vessel made of metal in the form of a square column, and isolating the outermost negative electrode plate from the battery vessel with a thin film, etc., made of synthetic resin having resistance against electrolytic solution. CONSTITUTION:Four negative electrode plates F composed mainly of a hydrogen storage alloy and four positive electrode plates H made from nickel hydroxide through a sintering process are laminated while separators G made from nonwoven cloth of nylon are interposed, wherein negative electrode plate must lie at the outermost layer. The electrode plate group configured as above is covered with a thermo- contractive tube of polyethylene as an anti-alkaline synthetic resin thin layer in such a way that the outermost negative electrode plate is enclosed, and this is left contracting. This electrode plate group is inserted in a battery vessel I of iron made in a square form which is subjected to nickel plating and works also as a negative electrode terminal. This is followed by further provision of leads C, J, J', rivet E as safety valve, cap B, and packing A, and finally an electrolytic solution is poured in. This prevents firing from negative electrode plates at the time of assembling.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a rectangular plate comprising a negative electrode plate carrying a hydrogen storage alloy, a positive electrode plate containing nickel hydroxide, manganese dioxide or the like as a main active material, a separator and an alkaline electrolyte. The present invention relates to a metal hydride storage battery.

[0002]

2. Description of the Related Art A hydrogen storage electrode is used as the negative electrode of a metal hydride alkaline storage battery.

This hydrogen storage electrode uses a hydrogen storage alloy capable of reversibly storing and releasing hydrogen as an electrode, and the electrochemical redox reaction of the hydrogen is used for the electromotive reaction of the negative electrode of the storage battery. To do. Hydrogen storage alloys used for hydrogen storage electrodes include intermetallic compounds such as LaNi ₅ , TiNi, Ti ₂ Ni, and TiMn ₂ , those in which the constituent elements of these intermetallic compounds are replaced with other elements, or amorphous. Quality alloys are used. When the composition of these hydrogen storage alloys is different, the properties such as hydrogen storage amount, equilibrium hydrogen pressure, and retention capacity characteristics when charging and discharging are repeated in the electrolytic solution change. Attempts have been made to improve the performance of the occlusion electrode.

This hydrogen storage electrode is made of a porous material by bonding the powders of these hydrogen storage alloys with an electrolytic solution resistant polymer, sintering at a high temperature, or filling a foam metal. Was.

In a metal hydride storage battery using an alkaline electrolyte, a negative electrode composed of these hydrogen storage electrodes and a positive electrode plate in which an active material mainly composed of nickel hydroxide is filled in a sintered nickel substrate or a nickel foam. , Laminate via a separator made of non-woven fabric such as alkali-resistant insulator to make a plate group, insert this plate group into a prismatic battery container made of nickel or nickel-plated iron, and store it. There was something to make.

In these metal hydride storage batteries, the amount of active material is adjusted so that the capacity limiting electrode at the time of battery discharge becomes the positive electrode.

In this way, during discharge, the discharge of the positive electrode ends before the discharge of the negative electrode, so that hydrogen gas is generated from the positive electrode before the negative electrode is polarized noble and oxygen gas is generated. Then, the hydrogen storage alloy is easily anodized at a remarkably noble potential such that oxygen gas is generated from its surface, and loses its activity. Therefore, it is advantageous to limit the discharge of the battery by the discharge capacity of the positive electrode, since it will prevent the noble polarization from becoming extremely noble as oxygen gas is generated from the negative electrode.

In these metal hydride storage batteries, the outermost part of the laminated electrode plate group is often the negative electrode plate rather than the positive electrode plate. The reason is as follows.

That is, since one surface of the outermost electrode plate is not opposed to the counter electrode, the active material in the part not opposed to the counter electrode has an internal resistance when discharged at a particularly large current. Since it is in a large position, it does not participate in the discharge reaction. When the discharge current is small, the ohmic loss due to the internal resistance is small, so that the active material in the part not facing the counter electrode also participates in the discharge reaction.

That is, when the discharge current of the electrode whose one surface does not face the other electrode changes, the active material utilization rate of the portion that does not face the other electrode changes significantly.

Therefore, if the entire surface of the positive electrode plate desired to be the capacity limiting electrode is opposed to the negative electrode, the active material has a small change in the active material utilization rate even if the magnitude of the discharge current changes. On the contrary, if there is a part of the positive electrode plate that does not face the negative electrode plate that is to be the capacity limiting pole, the change in the utilization rate of the positive electrode active material becomes large when the magnitude of the discharge current changes, and This is not preferable because the discharge capacity of 1 changes remarkably.

For this reason, the positive electrode plate which is desired to be the capacity limiting electrode has its entire surface facing the negative electrode plate, and at least a part of the negative electrode plate having an excessive discharge capacity is arranged at the outermost periphery of the electrode plate group. The surface that does not face the positive electrode plate is provided.

[0013]

As described above, in a storage battery having a metal prismatic battery container in which an electrode plate group in which at least a part of a negative electrode plate mainly composed of a hydrogen storage alloy is arranged at the outermost periphery is housed in a metal rectangular battery container. When the electrode plate group is inserted into the battery container and housed therein, there is a problem that ignition occurs from the negative electrode plate and the hydrogen storage alloy or the separator of the negative electrode burns.

Therefore, in such a storage battery, there has been a demand for means for preventing ignition from the negative electrode plate when the electrode plate group is housed in the prismatic battery container.

[0015]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention has a structure in which a negative electrode plate mainly composed of a hydrogen storage alloy and a positive electrode plate are laminated through a separator to form a prismatic electrode plate. In a metal hydride storage battery in which a negative electrode plate is present at the outermost part of the electrode plate group, the outermost negative electrode plate and the metal battery container are electrolytic solution resistant synthetic Provided is a prismatic metal hydride storage battery characterized by being isolated by a resin thin film or an electrolytic solution resistant metal thin plate.

[0016]

[Function] LaNi ₅ , ZrNi ₂ , and the like, and hydrogen storage alloys in which some of the constituent elements of these alloys are replaced with different elements have the property of being easily ignited by mechanical friction or impact.

Therefore, in the conventional metal hydride storage battery, the cause of ignition of the negative electrode plate when the electrode plate group is housed in the prismatic metal battery container is caused by the friction between the hydrogen storage alloy of the negative electrode plate and the prismatic metal battery container. Ignition of hydrogen storage alloy by.

Therefore, when the configuration of the present invention is adopted, the hydrogen storage alloy of the negative electrode plate is not directly rubbed with the metal battery container when the electrode plate group is inserted into the metal prismatic battery container, and as a result, The ignition of the hydrogen storage alloy is suppressed.

In addition, the metal battery container has a cylindrical shape,
In a metal hydride storage battery in which a strip-shaped positive electrode plate and a negative electrode plate are wound with a separator in between, a current collector is welded at multiple points to the end of the electrode plate protruding from the end face of this electrode plate group, and wound. There is a means for integrally supporting the rotated electrode plate group in a state of being pressed tightly and inserting it into a metal case. According to this means, the outer shape of the wound electrode plate group can be tightly pressed while keeping the outer diameter smaller than the inner diameter of the battery container. If such a configuration is adopted, the outermost negative electrode Since the plate can be inserted into the battery container without rubbing, it is possible to avoid the problem of ignition from the negative electrode as in the case of the prismatic battery.

However, in the case of a prismatic battery, it is necessary to use an electrode plate group in which flat plate-like electrodes are laminated, and in this electrode plate group, a current collector is often provided at the end of the electrode plate protruding from the end face thereof. Even if they are welded at the points, the electrode plates will fall apart, and it will not be possible to integrate them with tight compression. Therefore, when such an electrode plate group is directly inserted into the prismatic battery container, the negative electrode plate and the battery container come into contact with each other to generate strong friction, and ignition from the negative electrode plate occurs.

That is, the means of the present invention solves the problem peculiar to the prismatic metal hydride storage battery.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the drawings by the preferred embodiments. [Battery (A) of the Present Invention] FIG. 1 shows a rectangular sealed nickel-metal hydride storage battery (A) of the present invention in which the outer shape is rectangular and positive electrode plates and negative electrode plates are alternately laminated with a separator interposed therebetween. The schematic diagram of a vertical cross section is shown. In FIG. 1, I is an iron prismatic battery case plated with nickel and also serving as a negative electrode terminal. F is a negative electrode hydrogen storage electrode. G is
A separator made of nylon non-woven fabric. H is
This is a positive electrode sintered nickel hydroxide electrode.

The positive electrode plate H3 and the negative electrode plate F4 are laminated so that the negative electrode plate is the outermost layer through the separator G to form an electrode plate group. A heat-shrinkable tube made of polyethylene, which is a thin layer of alkali-resistant synthetic resin and has a thickness of 0.05 mm, is covered so as to cover the external negative electrode plate, and the tube is shrunk.

This electrode plate group was inserted into a prismatic metal battery container I to assemble a battery.

The total weight of nickel hydroxide contained in the three positive electrode nickel hydroxide electrodes E is about 3.9 g per cell. Therefore, assuming that nickel hydroxide follows a one-electron reaction, the theoretical capacity of the positive electrode of one battery is about 1.1 Ah. Nickel hydroxide 1
0.04 grams of cobalt hydroxide is added per gram.

The negative electrode plate C was manufactured as follows.

The hydrogen storage alloy has a composition of LmNi in atomic ratio.
The constituent elements were dissolved in a metal state in a high-frequency induction furnace in a vacuum so that _3.8 Co _0.7 Al _0.5 was obtained, cast, and then pulverized. Here, Lm is a lanthanum-rich misch metal which is a mixture of rare earth metals containing about 90% by weight of La. This alloy powder was dispersed in an aqueous solution of polyvinyl alcohol that functions as a thickener and a binder to form a paste. Then, this paste was applied to both sides of a nickel-plated iron punching metal, dried, pressed, and cut to manufacture a hydrogen storage electrode.

The weight of the hydrogen storage alloy contained in 4 sheets of the negative electrode plate of this battery is about 5.3 g.

From each positive electrode plate, a lead J made of a nickel-plated iron thin plate which is a conductive core that does not hold an active material is drawn out and welded. The lead J is positively connected by a rivet E which constitutes a safety valve. It is welded to the positive electrode lead connecting piece J ′ that has obtained continuity from the terminal.

The safety valve also serving as the positive electrode terminal and the battery lid have the following configurations. That is, the rivet E having a through hole is inserted into the through hole of the battery lid I having the through hole at the center through the packing A made of nylon having the through hole.
, And the rivet E is caulked by contacting the positive electrode lead piece inside the battery. A safety valve body D made of nitrile rubber is squeezed and placed on the through hole of the rivet, and the cap B having the gas discharge hole B1 also serving as a negative electrode terminal includes the safety valve body B inside and rivets. Welded on top of E.

When the internal pressure of the battery exceeds a specified value, the safety valve opens and the internal gas is released from the gas release hole B1.

Each negative electrode plate was independent. From each negative electrode plate, a lead C made of a nickel-plated iron thin plate which is a conductive core that does not hold an active material was pulled out and welded. C is welded to the inner surface of the battery lid I to obtain conduction of the negative electrode. The battery lid I has a 7 M containing 15 g / l LiOH and 0.6 M ZnO as an electrolytic solution whose entire circumference is welded and sealed by a laser at the upper end M of the battery container I.
1.6 ml of KOH aqueous solution was injected after inserting the electrode plate group into the battery container. [Battery (a) of the Present Invention] FIG. 2 is a schematic view of a vertical cross section of the prismatic metal hydride storage battery (a) of the present invention.

The battery (a) was replaced with the heat-shrinkable tube in the battery (a), and a nickel thin plate having a thickness of 0.05 mm was bent to have a U-shaped cross section, and the outermost negative electrode of the electrode plate group was used. The electrode plate group was housed so as to cover the plate, and this was inserted into a prismatic metal battery container I to assemble a battery. In the battery (a), the negative electrode lead C drawn from each independent negative electrode plate is collected and welded to the battery lid I. However, in the battery (a), the intermediate portion is replaced by the active material. The two negative electrode plates that were previously connected and integrated by the uncoated portion C ′ were bent at the portion of the uncoated portion C ′, and the negative electrode plate, through the metal thin plate L ′ that was in contact with the surface, A structure for obtaining electrical connection with the battery container I is adopted.
The other configurations are the same as those of the prismatic metal hydride storage battery (A) of the present invention. [Battery (C) of the Present Invention] FIG. 3 is a schematic diagram of a vertical cross section of the prismatic metal hydride storage battery (C) of the present invention.

In the battery (c), the following constitution was used in place of the active material-uncoated portion C'in the middle portion of the negative electrode plate and the nickel thin plate L'having a U-shaped cross section in the battery (a). That is, in the negative electrode plate next to the outermost negative electrode plate, the conductive core is extended from the lower portion of the negative electrode plate to the lower conductive core,
An active material uncoated portion C ″ which also serves as a protective metal thin plate of the outermost negative electrode plate is provided. Then, an active material uncoated portion C ″ which also serves as a protective metal thin plate of the outermost negative electrode plate is provided at the bottom of the battery. After crawling, stand up on the outside of the outermost negative plate,
The outermost negative electrode plate surface was covered. The electrode plate group thus constructed was inserted into the battery container I to assemble a battery. With this configuration, the outermost negative electrode plate is electrically connected to the battery case I through the active material non-coated portion C ″, and the negative electrode plate inside the outermost negative electrode plate is not coated with the active material. Electrical conduction is obtained from the battery container I by the portion C ″. Other than this configuration, the prismatic metal hydride storage battery (a) of the present invention is the same. [Conventional Battery (D)] The conventional prismatic metal hydride storage battery (D) uses the outermost negative electrode plate of the electrode plate group as a battery without using the heat-shrinkable tube L used in the battery (A) of the present invention. The structure was the same as that of the battery (a) of the present invention, except that the electrode plate group was inserted into the battery container I and assembled while being directly rubbed against the inner surface of the container I. [Conventional Battery (e)] In the conventional prismatic metal hydride storage battery (e), the outermost negative electrode plate of the electrode plate group is used as a battery without using the metal thin plate L ′ used in the battery (a) of the present invention. The structure was the same as that of the battery (a) of the present invention, except that the electrode plate group was inserted into the battery container I while directly rubbing against the inner surface of the container I to assemble the battery.

The above five types of batteries (a), (a),
1000 pieces of (C), (D), and (E) were assembled, and the frequency of ignition from the negative electrode plate was compared. The results are shown in Table 1.

[0036]

[Table 1] From Table 1, the outermost negative electrode plate and the metal battery container are separated by a heat-shrinkable tube which is an electrolytic solution resistant synthetic resin thin film, and a prismatic metal hydride storage battery (a) of the present invention, and electrolytic solution resistance. In the prismatic metal hydride storage batteries (a) and (c) of the present invention, which are separated by a thin metal plate, ignition from the negative electrode plate during battery assembly is effectively prevented. On the other hand, in the conventional prismatic metal hydride storage batteries (d) and (c) in which the outermost negative electrode plate and the metal battery container are not isolated, ignition from the negative electrode plate occurs when the battery is assembled.

In the above embodiment, the case where a rare earth hydrogen storage alloy having a specific composition is used has been described.
Rare earth hydrogen storage alloy with LaNi ₅ crystal structure,
Laves phase hydrogen storage alloys such as ZrNi ₂ are particularly apt to ignite due to friction and impact.Therefore, even in the case of hydrogen storage alloys in which some of the constituent elements of LaNi ₅ and ZrNi ₂ are replaced with other elements, the above The same effect as the example is obtained.

Further, the battery (a) of the present invention in the above embodiment
The heat-shrinkable tube L is used in the above. However, in the battery having this configuration, a metal thin plate L ′ having a U-shaped cross section used in the battery (b) of the present invention is used instead of the heat-shrinkable tube L. Even if it is adopted, the same effect as that of the above embodiment can be obtained.

Further, in the above-mentioned embodiment, the case where nickel hydroxide is used as the main component of the positive electrode active material has been described. However, in the case where manganese dioxide is used instead of nickel hydroxide, the above-mentioned embodiment is also used. The same effect as is obtained.

[0040]

According to the present invention, ignition from the negative electrode plate when assembling a prismatic metal hydride storage battery is prevented.

[Brief description of drawings]

FIG. 1 is a prismatic metal hydride storage battery of the present invention (a) in which a positive electrode plate and a negative electrode plate are alternately laminated with a separator interposed between them and an outermost negative electrode plate is protected by a heat-shrinkable tube.
FIG.

FIG. 2 is a prismatic metal hydride storage battery of the present invention in which the outermost negative electrode plate of the electrode plate group in which positive electrode plates and negative electrode plates are alternately laminated via separators is protected by a metal thin plate having a U-shaped cross section ( (A) A schematic view of a vertical section.

FIG. 3 shows an outermost negative electrode plate of an electrode plate group in which positive electrode plates and negative electrode plates are alternately laminated with a separator interposed therebetween, and an active material of a conductive core body of the negative electrode plate inside the outermost negative electrode plate is not coated. The schematic diagram of the vertical cross section of the prismatic metal hydride storage battery (c) of the present invention protected by the extended portion of the portion.

[Short description of reference signs] I Rectangular metal battery container F Negative electrode plate G Separator H Positive electrode plate L Heat shrinkable tube L'Cerical thin metal plate C "Cross section of negative electrode plate Extension

Claims (1)

[Claims] 1. An electrode group formed by laminating a negative electrode plate and a positive electrode plate, which are mainly composed of a hydrogen storage alloy, with a separator interposed therebetween, is housed in a prismatic metal battery container. A metal hydride storage battery having an outermost negative electrode plate, characterized in that the outermost negative electrode plate and the metal battery container are separated by an electrolytic solution resistant synthetic resin thin film or an electrolytic solution resistant metal thin plate. And prismatic metal hydride storage battery.