JPS59139574A - Plastic electrode of metal halogen cell - Google Patents

Abstract

PURPOSE:To obtain a plastic electrode hard to permeate for halogen of an active material by adding an adsorbent having adsorptivity to a composite made of plastic, carbon black, and graphite then molding them. CONSTITUTION:An adsorbent having adsorptivity is added to a composite made of plastic, carbon black, and graphite then they are molded. High-density polyethylene, straight chain-type low-density ethylene, polypropylene, ethylenepropylene copolymer, etc. are used as the plastic, for example; and zeolite, activated alumina, silica gel, diatomaceous earth, polyamide, magnesium silicate, etc. are used as the adsorbent, for example. Such an electrode can prevent the diffusion of halogen serving as an active material, e.g., bromine, thereby the energy efficiency of a cell is further improved and an electrode plate is prevented from being corroded, and it can be used for a long time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a carbon plastic electrode for a battery using a metal-halogen as an active material, and more specifically, to a carbon plastic electrode for a battery using a metal-halogen as an active material. The present invention relates to a novel plastic electrode made by adding the following.

BACKGROUND ART In recent years, batteries using metal-halogen as an active material have been attracting attention and being developed from the viewpoint of effective energy utilization. For example, as an example of a battery using a metal-halogen as an active material, FIG. 1 is an exploded perspective view showing the stacked structure of a metal-halogen electrolyte circulating type stacked secondary battery.

In FIG. 1, each electrode 1 and separator 2 are stacked as shown and sandwiched from both sides by aluminum clamping end plates 11, and the whole is integrally constructed with a clamping bolt 12 and a clamping nut 13. The electrolytic solution is supplied from the manifold 14 to the surface of the electrode section through the channels 15 and microchannels 19, and is also circulated by a circulation device (not shown). 16 is a resin fastening end plate, 17 is an electrode end plate,
18 is a terminal made of metal net.

A monovalent alkali metal such as Li or Na is used as the metal in a battery using the above metal-halogen as an active material.

K or divalent metals Zn, Cd, Ni, Co
, Fe, etc., and halogens include C1, Br,
I, etc. are used, and both non-aqueous solutions and aqueous solutions are used as electrolytes. In addition, carbon plastic electrodes have the advantage of being highly moldable and can be easily formed into various shapes, have good halogen resistance, and can be manufactured at low cost as electrodes for batteries that use the metal-halogen as the active material. It has been used because it is preferred. However, conventional carbon plastic electrodes have the disadvantage that when used for a long period of time, halogen diffuses through the electrode plates from one side of the electrode to the other, causing self-discharge and loss of battery function.

That is, when halogen permeates through the electrodes, a) the outer battery case that constitutes the battery corrodes; A) The energy efficiency of the battery decreases in proportion to the amount of halogen that passes through. c) Particularly in bipolar batteries, self-discharge occurs due to the penetration of halogen. 2) Diffusion of halogen into the electrode causes problems such as deterioration of the electrode.

As mentioned above, the present invention was invented in view of the conventional drawbacks when carbon plastic electrodes are used as electrodes using metal-halogen as active materials. The purpose is to provide

The gist of the present invention is a plastic electrode, which is formed by adding an adsorbent having adsorption properties to a composition of plastic, carbon black, and graphite, and molding the composition, and the plastic in the plastic electrode is made of high-density polyethylene. , one selected from linear low density ethylene, polypropylene, polyethylene-propylene copolymer, carbon black and graphite as an adsorbent, and one selected from zeolite, activated alumina, silica gel, diatomaceous earth, polyamide, and magnesium silicate. This is a plastic electrode made by adding seeds.

The present inventors have conducted various studies on electrode composition in order to solve the above-mentioned drawbacks when carbon plastic electrodes are used as electrodes for batteries with metal-halogen active materials. The electrode obtained by adding a type of adsorbent with good adsorption properties to the basic composition of plastic, carbon black, and graphite can significantly reduce the amount of halogen diffusion and improve the electrode resistivity. It was found that the energy efficiency of the battery was not so high compared to that without additives, and the energy efficiency of the battery was significantly improved.

Examples of adsorbents that have good adsorption properties and do not increase specific resistance include powdered synthetic zeolite, activated alumina, silica gel, powdered diatomaceous earth, polyamide, and powdered magnesium silicate.These adsorbents can be used as a base polymer (matrix). Polyolefins, i.e., high-density polyethylene, linear low-density polyethylene, polypropylene, polyethylene-polypropylene copolymers, and carbon plastic compositions consisting of a plastic material generally called polyolefin, carbon black, and graphite, have a range of 1 to 30%. to obtain an electrode composition. These compositions were thoroughly kneaded by heating (approximately 180°C) in a pressure kneader, then preheated to 150-170°C, and molded into electrodes using a pressurized hot press at approximately 100 mm. The resulting electrode is shown in Figure 2. As a result of measuring the amount of bromine diffusion using a bromine diffusion measuring device as shown in FIG. 1, it was discovered that by incorporating the above-mentioned adsorbent into carbon plastic, it has characteristics superior to ordinary carbon plastic electrodes.

FIG. 2 is a schematic diagram for explaining the bromine diffusion measuring device. In FIG. 2, reference numeral 21 denotes a carbon plastic sheet sample to be measured, which has a liquid contact area, a diameter of 20 cages, and a cage thickness of 1 cage. 26 is a bromine-free electrolyte container containing 251 bromine-free electrolyte 27 (ZnBr23 mol/l aqueous solution), and 24 is a bromine-containing electrolyte 26 (ZnBr23 mol/l +Br2
A bromine-containing electrolyte container containing 25 d of 3moA/l aqueous solution), 22 is a backing, 25 is a tightening bolt, and 28 is an electrolyte evaporation prevention lid.

The bromine-containing electrolyte container 24 is placed in a container 26 and is tightened with a tightening bolt 25 using a backing 22 to prevent liquid leakage.

Next, add the bromine-containing electrolyte 26 and the bromine-free electrolyte 27 to the same level (eliminate the difference in water head), and after a certain period of time, the amount of bromine Br2 in the bromine-containing electrolyte 26 diffused into the bromine-free electrolyte. is determined by iodometric titration.

Powdered synthetic zeolite as adsorbent, activated alumina 1
The amount of silica gel, powdered diatomaceous earth, polyamide, and powdered magnesium silicate should be determined from 1 to 100% based on the conductivity of the carbon plastic electrode, the electrode molding method, and the strength.
A blending amount of 60% is desirable, and it is preferable to reduce carbon black and graphite by an amount corresponding to this blending amount.

Zeolite is zeolite, a hydrous silicate with a chemical composition similar to feldspars.Although natural zeolite can also be used, powdered synthetic zeolite is preferable.Activated alumina has active alumina, active neutral, and active acidic zeolites. Side surfaces can also be used, and although the amount of diffusion is slightly inferior to when synthetic zeolite is used as an adsorbent, the electrode specific resistance is low. Furthermore, silica gel includes what is generally called silica gel, with or without a binder, and can be used, and diatomaceous earth that is untreated, treated with acid, treated with alkali, or coated in various ways can also be used.

The electrode according to the present invention (1) is formed and molded from plastic, carbon black, graphite, and an adsorbent, so it can suppress the diffusion of active materials such as halogens, such as bromine, and further improve the energy efficiency of the battery. be able to.

(2) Since halogen (bromine, etc.) diffused into the carbon plastic electrode plate can be reduced, corrosion of the electrode plate is eliminated and long-term use is possible.

(3) For the reason mentioned in (2) above, the same effect can be obtained for the electrode end plates and the outer case that constitutes the battery.

(4) It is a useful product that can be manufactured at low cost and can be applied to all batteries that use conductive plastic as electrodes, in addition to metal halogen batteries such as bromine-zinc batteries and chlorine-zinc batteries. It is a plastic electrode.

Next, the present invention will be further explained based on examples.O Example 1 The basic composition of the plastic electrode was to use high-density polyethylene as the base polymer (matrix) and add carbon black and higra-7ite to it. Synthetic zeolite powder was added as an adsorbent to make the composition as shown in Table 1 (Test 16 I-1 to 5), and the plastic electrode composition was heated at a starting temperature of 18
After sufficiently dispersing the adsorbent at 0°C for 3 minutes at 60 rpm and then at 90 rpm for 12 minutes, the kneaded sample was placed in the mold of a hot press and heated at 150 to 170°C for 5 minutes. Molded.

Next, using the above carbon plastic electrode, the amount of diffusion of bromine, which is the active material of a bromine zinc battery as a typical secondary battery, was measured using a bromine diffusion measuring device as shown in Figure 2, and the amount of diffusion is shown in Figure 6. The results were obtained.

As shown in FIG. 6, there is clearly a significant difference in the amount of bromine diffused between the sample with and without synthetic zeolite added as an adsorbent.

Example 2 Activated alumina was used as an adsorbent in Table 1 (Test plate ■-1~/
), a carbon plastic electrode sheet was prepared under the same kneading and molding conditions as in Example 1, and the amount of bromine diffused was measured using a bromine diffusion measuring device in the same manner as in Example 1. The results shown are obtained.

As shown in FIG. 4, it is clear that there is a significant difference in the amount of diffusion between those with and without activated alumina added as an adsorbent.

A carbon plastic electrode sheet was prepared under the same kneading and molding conditions as in Example 1, and the amount of bromine diffused was measured using a bromine diffusion measuring device in the same manner as in Example 1, as shown in FIG. 5.

As shown in FIG. 5, it is clear that there is a significant difference in the amount of diffusion between those with and without silica gel added as an adsorbent.

Example 4 Powdered diatomaceous earth was used as an adsorbent @1 table (testing company IV-1 to 3)
), a carbon plastic electrode sheet was prepared under the same kneading and molding conditions as in Example 1, and the amount of bromine diffused was measured using a bromine diffusion measuring device in the same manner as in Example 1. I got the diagram.

As shown in FIG. 6, it is clear that there is a significant difference in the amount of diffusion between those with and without powdered siliceous earth added as an adsorbent.

Example 5 Powdered polyamide was used as an adsorbent in Table 1 (Test A V
-1 to 2) at the indicated composition ratio, a carbon plastic electrode sheet was prepared under the same kneading and molding conditions as in Example 1, and the amount of bromine diffused was measured using a bromine diffusion measuring device in the same manner as in Example 1. Figure 7 was obtained.

As shown in FIG. 7, it can be seen that there is a clear and significant difference between the case where powdered polyamide was added as an adsorbent and the case where it was not added.

Example 6 Powdered magnesium silicate was added as an adsorbent in the proportion shown in Table 1 (test vine), and a carbon plastic electrode sheet was prepared under the same kneading and molding conditions as in Example 1.
Similarly, the amount of bromine diffused was measured using a bromine diffusion measuring device, and FIG. 8 was obtained. As shown in FIG. 8, it is clear that when powdered magnesium silica is added, the amount of deep diffusion is smaller than when it is not added.

In addition, Fig. 9 shows the relationship between time and bromine diffusion h) for each representative adsorbent in Examples 1 to B, and Fig. 10 shows a graph of the specific resistance values of Plus Deck electrodes containing various adsorbents. show.

[Brief explanation of the drawing]

Figure 1 is an exploded perspective view showing the laminated structure of a metal-halogen electrolyte circulation type stacked secondary battery, Figure 2 is a schematic diagram of a bromine diffusion measuring device, and Figures 3 to 8 are examples 1 to 2, respectively. Figure 9 is a graph showing the relationship between time and the amount of bromine diffused in a carbon plastic electric rod prepared by adding zeolite, activated alumina, silica gel, diatomaceous earth, polyamide, and powdered magnesium silicate as adsorbents. 1 is a graph showing the relationship between time and the amount of bromine diffusion of plastic electrodes containing typical adsorbents in the above examples, and FIG. 10 is a graph of specific resistance values of plastic electrodes containing various adsorbents. : Electric plate, 2: Separator, 17: Electrode end plate, 21: Measurement sample, 26: Bromine-free electrolyte container, 24: Bromine-containing electrolyte container, 26: Bromine-containing electrolyte, 27: Bromine-free electrolyte. Substitute. Person Patent attorney Sanro Kimura 1, Indication of the case Japanese Patent Application No. 11362/1989 2, Name of the invention Plastic electrode for metal halogen battery 3, Relationship with the person making the amendment A'1 %FF Applicant name (L (,2,) (<5in) Meidensha Co., Ltd. 4,
Agent (Delivery 1) Showa month (2) "Plastic electrode" in lines 10-11 of page 4 of the specification is corrected to "glass electrode". (3) Page 12-16 of the same page Correct “polyethylene” in line 5 to “ethylene”. (4) Correct “polyethylene-polypropylene J” in lines 14 to 15 of page 5 of the same year to “f ethylene-propylene”. (5) Page 6 of the same year Correct “Incorporated into carbon plastic” on the 5th line to “Incorporated into carbon plastic composition.” (6) Change “(matrix)” in the 3rd line of page 9 to “(
matrix)”. (7) rMFR on page 16, line 6 from the bottom: 5.3
Correct "rMFR: 5.3 710 minutes". (8) Correct Phase 1 of the drawing as per the corrected drawing. Attachment Claims (Amendment) (1) A plastic electrode for a metal-no-logen battery, characterized in that it is formed by adding an adsorbent having adsorption properties to a composition consisting of plastic, carbon black, and graphite and molding the same. (2) The metal halogen battery according to claim 1, wherein one selected from zeolite, activated alumina, silica gel, diatomaceous earth, polyamide, and magnesium silicate is added as the adsorbent. plastic electrode. (3) The metal halogen battery according to claim 1, wherein the plastic is made of one selected from high-density polyethylene, linear low-density polyethylene, polypropylene, and ethylene-propylene copolymer. plastic electrode.

Claims (3)

[Claims] (1) A plastic electrode for a metal halogen battery, characterized in that it is formed by adding an adsorbent having adsorption properties to a composition consisting of plastic, carbon black, and graphite and molding the mixture. (2) As the adsorbent, zeolite, activated alumina,
The plastic electrode for a metal halogen battery according to claim 1, characterized in that it contains one selected from silica gel, diatomaceous earth, polyamide, and magnesium silicate. (3) The metal halogen battery according to claim 1, wherein the plastic is made of one selected from high-density polyethylene, linear low-density polyethylene, polypropylene, and polyethylene-polypropylene copolymer. plastic electrode.