JPS6271175A - Zinc-halogen battery - Google Patents

Abstract

PURPOSE:To realize shortening time from discharging finish to charging start, by installing a halogen-proof filter in an electrolytic solution-return passage, which goes from a battery part to an electrolytic solution jar, so that the electrolytic solution returns through the filter to the electrolytic solution jar. CONSTITUTION:A swelling part 8 is formed on a return pipe 6, and a halogen- proof filter 9 comprising teflon and titanium is installed inside the swelling part 8 so that electrolytic solution coming from a battery part 3 returns through the filter 9 to an electrolytic solution jar 4. Thus, zinc falling off from a zinc plate at the final period of discharge is securely captured at the filter and swiftly dissolved into a flow of the electrolytic solution returning to the electrolytic solution jar. Therefore, without zinc, graphite and the like mixed into the electrolytic solution, which is supplied into the battery part from the electrolytic solution jar, time from discharging finish to charging start can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a zinc-halogen battery, and in particular, it captures zinc that falls off without being eluted from the zinc electrode at the end of discharge, dissolves it early, and charges the battery after the lightning strike ends. This makes it possible to shorten the time it takes to start.

Conventional technology: A zinc-halogen battery is equipped with halogen as a positive electrode active material, zinc is used as a negative electrode active material, and an aqueous solution containing zinc halide as the main component is circulated as an electrolyte. Gas is generated, metallic zinc is deposited at the zinc electrode, halogen gas is ionized at the halogen electrode during discharge, and zinc is eluted and ionized at the zinc electrode.

As such batteries, zinc-chlorine batteries, zinc-bromine batteries, etc. are known.

In all zinc-halogen batteries, charging and discharging are performed by supplying an electrolytic solution from an electrolytic solution tank with a pump and circulating it to a battery section in which a zinc electrode plate and a halogen electrode plate are arranged opposite each other. For example, in a zinc-halogen battery, as shown in Figure 3, a zinc electrode plate (1) made of hard graphite or titanium and a chlorine electrode plate (z) made of porous graphite or porous titanium plate (z are all placed opposite each other in the battery part ( 3) Formation of a chlorine electrode plate (as shown by the arrow in the figure) using an aqueous solution containing zinc chloride as an electrolyte (
2) is passed through and is supplied between the two electrode plates (11 (2).The electrolyte is supplied from the electrolyte tank (4) to the battery using a pump (5) as shown in Figure 4. Part (3) Why? The electric group is circulating in the direction of the arrow shown to 7-11L. During charging, the metal is heated by the zinc electrode plate. Zinc is precipitated, chlorine gas is generated with a chlorine electrode plate, zinc is eluted and ionized with the zinc electrode plate during discharge, and chlorine gas is ionized with the chlorine electrode plate.

Problems to be Solved by the Invention In zinc-halogen batteries, metallic zinc is precipitated at the zinc electrode during charging as described above, and the precipitated zinc is eluted during discharging, but the problem is that zinc does not dissolve uniformly during discharging. Even when the discharge end voltage is reached, zinc (7) remains on the surface of the zinc electrode plate (1) as shown in FIG. This remaining friend zinc (7) falls off from the final stage of discharge, is carried by the flow of electrolyte, and enters the electrolyte tank. A part of the electrolyte remains in the electrolyte tank, and a part rides on the flow of the electrolyte and is sent back to the battery section. In addition, in batteries using hard graphite or porous graphite for the electrode plates, graphite and carbon fall off from the electrode plates and become mixed into the electrolyte.

When such an electrolyte enters the battery part, in zinc-chlorine batteries, some of the zinc, graphite, carbon, etc. adhere to the back side of the chlorine electrode plate that allows the electrolyte to pass through, reducing the permeability of the electrolyte. Part of the chlorine passes through the electrode plate and flows through both electrode plates. In addition, in a chlorine-bromine battery, zinc, graphite, carbon, etc. flow between the two electrode plates together with the electrolyte. If charging is started in such a state, zinc, graphite, carbon, etc. flowing with the electrolyte will adhere to the zinc electrode plate and not only interfere with the uniform deposition of zinc but also promote the growth of zinc dendrites and cause damage inside the battery. There is a problem with short circuits.

In order to prevent this, conventional methods have been to apply an external current between the two electrode plates of the battery after discharging to dissolve the zinc remaining on the zinc electrode plate, or to lower the pH of the electrolyte to make it easier to dissolve the zinc. Or, the time from the end of discharging to the start of charging is lengthened. However, all of these means have the disadvantage that it takes a long time from the end of discharging to the start of charging.

Means for Solving the Problems In view of the present invention, as a result of various studies, the zinc that falls off from the zinc electrode plate at the end of discharge is quickly dissolved by trapping 1- to shorten the time from the end of discharge to the start of charging. We have developed a zinc-halogen battery that can be used for charging and discharging by circulating electrolyte from the electrolyte tank to the zinc-halogen battery part using a pump. This system is characterized in that nine circuits are equipped with halogen-resistant filters, and the electrolyte is returned to the electrolyte tank through the filter.

That is, as shown in FIG.
3) Pour the electrolyte into the electrolyte tank (4) through the return pipe (6).
In zinc-halogen batteries that charge and discharge by circulating the electrolyte, a bulge (
8) Fully formed, halogen-resistant filter (9) made of Teflon or titanium is completely attached to the bulge (8), and the electrolyte from the battery part (3) is filtered (9)? through which it returns to the electrolyte tank (4).

The installation location of the halogen-resistant filter is not limited to the middle of the return pipe; for example, as shown in Fig. 2, the installation location is not limited to the middle of the return pipe.
6) Electrolyte tank (4) where the lower end and electrolyte tank (4) are connected
A bulge (8) may be formed within the bulge (8), and a halogen-resistant filter (9) may be mounted within the bulge (8).

A halogen-resistant filter is attached to the return pipe that returns the electrolyte from the battery section to the electrolyte tank, and by passing the electrolyte returned from the battery section to the electrolyte tank through the filter, it is prevented from falling off the zinc electrode plate during the first discharge bed period. The removed zinc is reliably captured by the filter and quickly dissolved by the flow of electrolyte back into the electrolyte tank. Furthermore, the filter can reliably capture not only zinc that has fallen off, but also graphite and carbon that have fallen off from the electrode plates. As a result, the electrolyte pumped from the electrolyte tank to the battery section does not contain zinc, graphite, carbon, etc., so even if the time from the end of discharging to the start of charging is shortened, zinc deposition on the zinc electrode plate does not occur. uniformity, and zinc dendrite growth is effectively prevented.

The amount of zinc that dissolves from the zinc electrode plate is usually in the order of several tens of microns, and can be sufficiently captured by a commercially available regular Teflon filter as well as a halogen-resistant filter. If more efficient removal is required, it is recommended to increase the diameter of the bulge formed in the return pipe and attach a titanium or Teflon filter of several hundred mesh to this.

Example Electrode active area: 300i with a zinc electrode made of a hard graphite plate and a chlorine electrode made of a porous graphite plate placed opposite each other.
Using a 500W class zinc-chlorine battery with 30 single cells arranged in series, the electrolyte (2 mo
l/1ZnC4z+1mol/AKCL+2mol/1
A photodischarge test was conducted on the battery of the present invention in which NaC4Jk was circulated through the battery section, a bulge was formed in the return pipe from the battery section to the electrolyte phase, and a commercially available Teflon filter was attached as shown in Figure 1. I did it.

Electrolyte is supplied at 600 ml/ltrm per cell,
After light N was carried out for 8 hours at a current density of 30 mA/cJ, discharge 1'l: 27 mA/'c++! This was repeated a total of 14 times at a current density of about 8 hours (-) to investigate the relationship between the time required to fully discharge and then start charging and short circuits in the battery. Table 1 shows a comparison between the time from complete discharge to the start of full charging and the short circuit in the battery section for conventional batteries with the sub-fluorocarbon filter removed.

Table 1 Batteries of the present invention 2 10 4
None〃 6 〃 〃 8 〃 Conventional battery 2 40〃
4 10 〃 6 None 8 None As is clear from Table 1, it is necessary to dissolve zinc for more than 6 hours from complete discharge to the start of charging with the conventional battery, but with the battery of the present invention, it is necessary to dissolve the zinc from complete discharge to start charging. After about 4 hours of zinc dissolution, there were no short circuits in the battery, and
It can be seen that the time from the end of charging to the start of charging can be significantly shortened by 5 times.

Effects of the Invention According to the present invention, it is possible to completely shorten the time from the end of discharging to the start of charging of a zinc-halogen battery, and it has the remarkable effect of significantly improving the usage efficiency in terms of battery operation. It is.

[Brief Description of the Drawings] Fig. 1 is an explanatory diagram showing one example of the battery of the present invention, Fig. 2 is an explanatory diagram showing another example of the battery of the present invention, and Fig. 3 is an explanatory diagram showing an example of the battery of the present invention.
FIG. 4 is a side sectional view showing an example of a chlorine battery section, and is an explanatory diagram showing an example of a conventional battery. 1 Zinc electrode plate 2 Chlorine electrode plate 3 Battery part 4 Electrolyte tank 5 Return pipe 6 Zinc 8 Swelling part 9 Filter Figure 3 Figure 4 Figure 5 Hand vL: Neyama - Positive % (Method) % formula % 2. Name of the invention Zinc-8 [1 Gen Battery,'' September 3, 1985 (IiJ dispatch El: Inwa 61 year 9
30th day of the month) Contents of the amendment Brief explanation of the drawings Figure 1 is an explanatory diagram of one example of the battery of the present invention, Figure 2 is an explanatory diagram showing another example of the battery of the present invention, and Figure 3 is a conventional zinc-
FIG. 4 is a side sectional view showing an example of a chlorine battery section, FIG. 4 is an explanatory diagram showing an example of a conventional battery, and FIG. 5 is an explanatory diagram showing a phenomenon in which zinc falls off from a zinc-chlorine battery section. 1, zinc electrode plate 2, chlorine electrode plate 3, battery part 4, electrolyte tank 5, return pipe 6, zinc 8, bulge part 9, filter

Claims (1)

[Claims] In batteries that charge and discharge by circulating the electrolyte from the electrolyte tank to the zinc-halogen battery section using a pump, a halogen-resistant filter is installed in the electrolyte return circuit from the battery section to the electrolyte tank, and the electrolyte is passed through the filter. A zinc-halogen battery characterized by being returned to an electrolyte bath.