JPH07326393A - Zinc-bromine battery divided in unit - Google Patents

Abstract

PURPOSE:To reduce the thickness of an end plate electrode without deteriorating battery reliability, and increase energy density per weight in a zinc-bromine battery obtained by stacking a plurality of cells formed of a separator clamped between bipolar type intermediate electrodes having a flow passage for electrolyte circulation and a frame body. CONSTITUTION:A peripheral frame 22 is provided along the external surface of an end plate electrode, and an electrode 21 is divided into four sections. In addition, a sealing reinforcement frame 23 is laid in space among the four sections. As a result, the center of the end plate electrode is pressed with the frame 23 and at the same time, acts as a reinforcement, thereby enhancing the strength of the electrode 21. When the electrode 21 is divided into four sections as mentioned, the occurrence of maximum strain is reduced to 1/4 or lower than the case of the conventional design shown in the illustration (a). According to this construction, necessary strength can be maintained with the overall thickness of the end plate electrode equal to 1/2 or less.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention accumulates excess power at night,
The present invention relates to a new type of secondary battery for power storage that discharges electric power at the peak of daytime power consumption so as to keep the generated power of a power plant constant, and more particularly to a structure of stacked battery bodies of a zinc-bromine battery.

[0002]

2. Description of the Related Art A zinc-bromine battery is an aqueous secondary battery which uses zinc for the negative electrode and bromine for the positive electrode as an active material.
The principle is shown as follows. Positive electrode reaction 2Br ⁻ ← → Br ₂ + 2Br ⁻ Negative electrode reaction Zn ²⁺ + 2e ← → Zn where → indicates charging and ← indicates discharging.

Polyethylene (hereinafter PE) is used as an electrode material.
PE) CB: GF = 6: in a weight ratio of carbon black (hereinafter referred to as CB) and graphite (hereinafter referred to as GF) to give conductivity as a binder.
A mixture of 1: 3 is molded and used as an electrode material.

On the positive electrode side, carbon cloth is attached to the electrode surface by thermocompression bonding in order to reduce the reaction overvoltage of bromine. Bromine generated during charging at the positive electrode will dissolve if it comes into direct contact with the zinc portion electrodeposited on the negative electrode side. This is called self-discharge. As a result, the amount of zinc that is charged in the battery and electrodeposited decreases, and the battery efficiency decreases.

As a measure against the decrease in efficiency, it is possible to perform charging and discharging by ion exchange in the separator portion via a separator between the positive and negative electrodes. Furthermore, since the liquid in the positive and negative electrodes is circulated during charging and discharging, it has a tank structure independent of the positive and negative electrodes. The composition of this solution is zinc bromide (ZnB
It is a mixed aqueous solution of r ₂ ) + bromine complex.

The battery body (battery unit) is constructed as shown in FIG. 3, and charging / discharging is performed in the stack 1 in which electrodes are laminated. A stack is a stack of a plurality of cells (between a pair of electrodes) in series, and there is a collector electrode plate (electrical extraction part) called an end plate electrode 2 at both ends, and electrodes in the middle are on the front and back. It is composed of what is called an intermediate electrode (bipolar type electrode) which also serves as positive and negative electrodes.

Around the electrode plate, there is formed a channel structure for maintaining insulation and a necessary distance between electrodes and for securing a flow path of liquid, and for preventing the liquid from being discharged to the outside, a seal is provided outside. I need a frame. In FIG. 3, reference numeral 3 denotes a tightening end plate which is superposed on the end plate electrode 2, and these are tightened with a bolt 4 and a nut 5 to be integrally formed.

[0008]

In the battery having the structure shown in FIG. 3, the internal pressure of the battery unit is reduced due to the drop of the battery unit and the electrolytic solution tank and the specific gravity of the electrolytic solution when the pump is stopped during operation, and the end plate electrode At the welding interface between the second electrode portion and the frame portion, the amount of strain is maximized, causing deformation.
Hereinafter, the reduced pressure in this unit is referred to as negative pressure.

In the current structure of the end plate electrode 2 as shown in FIG. 3, when an attempt is made to improve the reliability by enlarging the battery unit or the like, the influence of the negative pressure is taken into consideration and the entire end plate electrode is You have to increase the thickness. Therefore, there is a drawback in that the energy density per weight and the cost are adversely affected.

The present invention has been made in view of the above points, and an object thereof is to provide a split type zinc-bromine battery in a unit in which end plate electrodes can be thinned without impairing the reliability of the battery. is there.

[0011]

According to the present invention, an outer peripheral frame portion having a flow path for circulating an electrolytic solution is provided on each outer periphery of an intermediate electrode, a separator and an end plate electrode, and the intermediate electrode, the separator and the end plate electrode are provided. Each of which is divided into a plurality of parts, and a reinforcing frame portion is provided at the divided portion to form a framed intermediate electrode, a framed separator and a framed end plate electrode, and a framed separator is sandwiched between the framed intermediate electrodes. It is characterized in that a plurality of the unit cells are laminated and the framed end plate electrodes are arranged at both ends of the laminated body in the laminating direction to be integrated.

[0012]

The reinforcing frame portion provided at the divided portion of the end plate electrode acts so as to press the center of the end plate electrode, so that the strength of the battery main body is improved. For example, in the case of four divisions, if the thickness is the same as the conventional electrode, the maximum strain that occurs is 1 /
Therefore, the required strength can be obtained when the total thickness of the end plate electrodes is 1/2 or less.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In the present invention, one in which the inside of the battery unit is separated into several (for example, four) is regarded as one unit. As shown in FIG. 1B, the outer peripheral frame portion 2 is provided on the outer periphery of the end plate electrode.
2, the electrode part 21 is divided into separate parts, and the reinforcing frame part 23 for sealing is provided between them.

The center of the end plate electrode is pressed by the reinforcing frame portion 23, and at the same time, it becomes a reinforcing material, so that the strength is improved. When it is divided into four as in this example, the maximum strain generated is 1/4 or less as compared with the current type if the thickness is the same. Therefore, the required strength can be obtained when the thickness of the entire end plate electrode is 1/2 or less. Incidentally, FIG. 1A shows a conventional end plate electrode, 11 is an electrode portion, and 12 is a frame portion.

The outer peripheral frame portion 22 and the reinforcing frame portion 23 of the structure shown in FIG. 1B are provided not only on the end plate electrodes but also on the intermediate electrodes and the separators as shown in FIG. 2B.

The number of divisions of the end plate electrode, the intermediate electrode, and the separator is not limited to four, but may be another division number.

[0017]

As described above, according to the present invention, an outer peripheral frame portion having a flow path for circulating an electrolytic solution is provided on each outer periphery of the intermediate electrode, the separator and the end plate electrode, and the intermediate electrode, the separator and the end are provided. Each of the plate electrodes is divided into a plurality of parts, and a reinforcing frame portion is provided at the divided portions to form a framed intermediate electrode, a framed separator and a framed end plate electrode, and a framed separator is provided between the framed intermediate electrodes. Since a plurality of single cells sandwiched are stacked and the framed end plate electrodes are integrated at both ends in the stacking direction of the stack, the end plate electrodes can be made thin without impairing reliability, Cost performance and energy density per weight are improved. Therefore, a large battery area can be obtained with one battery unit, and the entire system can be made compact.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part showing an embodiment of the present invention.

FIG. 2 is a schematic diagram of a battery internal structure showing the overall configuration of one embodiment of the present invention.

FIG. 3 is a configuration diagram showing deformation of an end plate electrode due to negative pressure in a conventional zinc-bromine battery.

[Explanation of symbols]

 21 ... Electrode part 22 ... Peripheral frame part 23 ... Reinforcing frame part

Claims (1)

[Claims] 1. An outer peripheral frame portion having a flow path for circulating an electrolytic solution is provided on each outer periphery of an intermediate electrode, a separator and an end plate electrode,
The intermediate electrode, the separator and the end plate electrode are each divided into a plurality of parts, and a reinforcing frame portion is provided at the divided portion to form a framed intermediate electrode, a framed separator and a framed end plate electrode. A unit-divided type in which a plurality of unit cells each having a framed separator sandwiched therebetween are stacked, and the framed end plate electrodes are integrated at both ends in the stacking direction of the stacked body. Zinc-bromine battery.