JPH02142070A - Liquid circulation type metal-halogen battery - Google Patents

Abstract

PURPOSE:To prevent the adhesion of a separator membrane and an electrode plate in the operation time of the battery by injection-molding separator holding projections integrally with a separator frame to function in place of separator posts which are smashed by metal molds when the separator frame is injection- molded. CONSTITUTION:Separator posts 20a1 positioned on the dotted lines 100 at the periphery of a separator membrane 20 which is held by metal molds are squeezed and broken when a separator frame 50 is injection-molded. Therefore, projections 54 for holding the separator membrane 20 in place of the smashed separator posts 20a1 are formed integrally to the separator frame 50 when it is injection-molded. As a result, the projections 54 prevent the contact of both side electrode plates and the separator membrane 20 when the battery is operated, and the flow of the electrolyte is never blocked.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid circulation type metal-halogen battery, and particularly to the structure of a separator that separates a positive electrode side and a negative electrode side in a reaction tank.

[Prior Art] Metal-halogen batteries have been developed that use halogens such as bromine, which have high solubility in electrolytes and excellent electrode reaction characteristics, as the positive electrode active material and metals such as zinc as the negative electrode active material.
Due to its many advantages such as ease of handling and high energy density, it is attracting attention as a driving source for electric vehicles, for example.

FIG. 6 shows the principle structure of a general metal-halogen battery disclosed in Japanese Patent Application Laid-Open No. 57-199167.

Zinc is used as the metal on the negative electrode side in the illustrated example,
An electrochemical reaction expressed by the following formula is performed via an electrolytic solution 18 between a positive electrode side reaction tank 14 and a negative electrode side reaction tank 16 in which the positive electrode 10 and the negative electrode 12 are disposed, respectively.

(Positive electrode) 2Br :Br 2+2e (Negative electrode) Zn ”+ 2 e ;:Zn ・
・(1) Charging (total) Zn2"+2Br;? Zn+Br discharge In such a metal-halogen battery, a zinc bromide ZnBr2 aqueous solution is used as the electrolyte 18, and a conductivity improvement agent, bromine is used as the electrolyte 18. Complexing agents, dendrite inhibitors, etc. are added.

At the time of charging, in the reaction tank 14.16, the above-mentioned formula 1 →
A charging reaction shown by is performed, and on the positive electrode 10 side, bromine B r 2
is generated and dissolved in the electrolytic solution 18, and on the other hand, on the negative electrode 12 side, zinc Zn is precipitated and a deposited layer of zinc is formed on the negative electrode 12.

Furthermore, during discharging, a reaction opposite to that during charging takes place, which is indicated by -, and on the positive electrode 10 side, bromine Br2 is reduced and becomes bromine ions Br-, which are dissolved in the electrolysis 1fjc18, and on the negative electrode 12 side, zinc ions are reduced. The precipitated layer is oxidized and zinc ions Zn
2+ and dissolves in the electrolyte 18.

The interiors of the reaction vessels 14 and 16 in which such electrical reactions occur are separated by separator membranes 20 to prevent self-discharge caused by bromine B r 2 generated during charging.

In order to prevent self-discharge, this separator film 20 allows various ions in the electrolytic solution 18 to pass through, but blocks the penetration of bromine B r 2 dissolved therein. An ion exchange membrane or a porous membrane is generally used as the separator membrane 20, but a porous membrane is desirable from the viewpoint of reducing the internal resistance of the battery.

The electrolyte circulation type battery includes a positive electrolyte storage tank 22 and a negative electrolyte storage tank 24 for storing energy obtained through chemical reactions during charging.

The positive electrode side electrolyte storage tank 22 forms an electrolyte circulation path with the positive electrode side reaction tank 14 via piping 26, 28, and the positive electrode side reaction tank 1 is
The positive electrode side electrolyte 18a reacted in the storage tank 22
The electrolyte 18a in the storage tank 22 is sent to the reaction tank 14.
is supplied to.

Here, if a bromine complexing agent is added to the electrolytic solution 18, the bromine B r 2 generated during charging is complexed and precipitated as a complex compound 32 insoluble in the electrolytic solution 18. The complex compound 32 is sequentially precipitated and stored in the bottom of the storage tank 22 as a complex storage section 34.

Further, a valve 3 is connected between the complex storage section 34 and the pipe 28.
A complex feed tube 38 having 6. This valve 36 is normally open, and the complex compound 32 precipitated in the complex storage section 34 is sent out through the pipe 28 toward the positive electrode side reaction tank 14 for discharge.

Further, the negative electrode side electrolyte storage tank 24 similarly forms an electrolyte circulation path with the negative electrode side reaction tank 16 via piping 40, 42, and uses a pump 44 provided in the circulation path. Negative electrode side electrolysis iiν reacted in the negative electrode side reaction tank 16
18b is sent to the storage tank 24, and a new electrolyte 18b is reacted from the storage tank 24. 116 is being supplied.

In this way, this metal-halogen battery has storage tanks 22,
A sufficient amount of electrolyte 18 is stored in 24, and the stored electrolyte 18 is
When charging using
A bromine complex compound is stored in the complex storage section 34 and a zinc deposit layer is formed on the negative electrode 12 to store electric power.

Also, during discharge, the bromine complex compound 32 stored in the complex storage section 34 is sent out to the positive electrode side reaction tank 14,
The complex compound 32 and negative l! ! Using the zinc precipitated layer formed on 1112, the discharge reaction shown in the first equation can be performed and the charging power can be released.

By the way, when a metal halogen battery with the above-mentioned principle configuration is actually used as a drive source for an electric vehicle,
The reaction tank 14, 16 has a plurality of cells as a basic unit consisting of both electrodes 10° 12 and a separator stacked, and electrolyte is supplied to the plurality of cells in the reaction tank from a common electrolyte storage tank on both electrode sides. It will be supplied in circulation.

Therefore, as shown in FIG. 7(A), the separator film 20
is formed so that its peripheral edge is held by the frame 50,
The positive electrode side electrolyte flows into each stacked cell through a manifold 50a formed in this frame 50 and a rectifier 52.

Normally, an injection molding method is used to manufacture the separator frame 50 that holds the separator film 20, and the separator film 20 is fixedly held in upper and lower molds, and molten plastic or the like is placed in the hollow part of the mold. is injected into the separator film 20.
The end portion of the frame portion 50 was joined to the end portion of the frame portion 50.

Here, as described above, a large number of cells each consisting of both electrodes and a separator are stacked in the reaction tank, and therefore the separator frame 50, which is the area where the electrolytic solution exists, and the electrodes 10°12 The space formed by this is very narrow. Therefore, if the smooth separator film 20 and each electrode are directly opposed to each other in an exposed state, the separator film 20 may adhere to the adjacent electrodes 10.12 due to the deflection of the separator film 20 that occurs during battery operation. , there arises an inconvenience that the smooth flow of the electrolyte on the electrode side is obstructed.

For this reason, as shown in FIG. 3(A), posts (protrusions) 20a are generally integrally formed on both sides of the separator film 20 at predetermined intervals to maintain a distance from adjacent electrodes. This prevents the separator film 20 from sticking to the electrodes.

[Problems to be Solved by the Invention] As described above, in the conventional battery, the □ post 20a integrally formed with the separator film 20 plays the role of maintaining a constant distance from the electrode even during battery operation. however,
During injection molding of the frame 50 onto the separator film 20 described above, the vicinity of the periphery of the separator [20] must be held down by the upper and lower molds, resulting in the problem that the separator post 20a in this area is crushed.

In FIG. 7(A), the separator film 20 is removed during injection molding.
The dotted line 100 indicates the position of the mold that holds the peripheral edge of the separator post 20ab, and it can be seen that the separator post 20ab located in the portion held by this mold is crushed as shown by . The same figure (B) shows the l-11 cross section of the same figure (A), and the separator post I-20 located in the part held by the mold
The electrodes a and b are crushed and are no longer able to maintain the distance between them and the electrodes located on both sides thereof.

If the separator constructed in this way is used as is in a battery, the crushed portions of the posts will adhere to the electrode plates adjacent on both sides, impeding the flow of electrolyte within the cell, and as a result, improving the overall performance of the battery. The disadvantage was that it significantly reduced the

As a countermeasure for these inconveniences,
In Publication No. 1, a concave clearance hole corresponding to the convex projection of the separator film is formed in the mold that holds the separator, so that the separator post will not be damaged even if the separator film is pressed between the upper and lower molds. An injection molding method for a separator frame is disclosed.

If this method is carried out, it is theoretically possible to form a frame without crushing the separator posts, but in order to do so, the separator film must be formed with as high precision as the mold. Otherwise, the fitting with the escape hole of the mold will not be achieved properly, making it impossible to reliably protect the separator post.

However, since this kind of post-attached separator film is made in one batch and continuously by embossing a long sheet-like material, it is almost impossible to maintain high dimensional accuracy of each separator post. .

Therefore, the method of providing escape holes in the mold as described above has a problem with the mutual positional relationship in terms of dimensions with the separator posts, and the actual situation is that it is difficult to reliably protect the separator posts.

The present invention was made in view of the above-mentioned conventional problems, and its purpose is to compensate for the effect of a separator post that is damaged during injection molding of a separator frame with a simple structure, and to protect the separator film and its both sides when using a battery. It is an object of the present invention to provide a liquid circulation type metal-halogen battery that can reliably prevent deterioration of the electrolyte flow due to adhesion with the located electrodes.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a separator for self-discharge prevention and a plurality of cells each including a positive electrode and a negative electrode disposed on both sides of the separator. In a liquid circulation metal-halogen battery equipped with a reaction tank that performs a predetermined charging/discharging reaction via an electrolytic solution that is stacked and independently circulated and supplied to each electrode side, the separator holds the side electrodes at a predetermined interval. The post includes a separator film formed on both sides thereof and a separator frame injection molded to surround and hold the periphery of the separator film, and the separator frame supporting the separator film includes an injection molding mold of the separator film. It is characterized by having a plurality of protrusions integrally injection molded into the crushed mold mark.

[Function] According to the present invention configured as described above, even if the posts of the separator 111 that hold the mold are crushed during injection molding of the separator frame, there is a protrusion that acts as a substitute for the crushed posts. Since the separator support plate is injection molded together with the separator frame, the protrusions prevent contact between the electrode plates on both sides and the separator membrane during use of the battery, and the flow of the electrolyte is not hindered.

The separator supporting protrusions are completely newly formed together with the separator frame, regardless of the dimensional accuracy of the separator posts on the separator film, so that the separator can be reliably supported without any interference with its function in relation to the separator film. It can prevent contact between the membrane and the electrode.

[Example] Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

In the figure, the same reference numerals are given to the same components as those of the conventional device, and the explanation thereof will be omitted.

FIG. 1 shows the structure of a separator in a liquid circulation type metal-halogen battery according to the present invention. Note that there is no substantial difference from the conventional device except for this separator structure.

As described above, the separator film 20 and the separator frame 50 are joined together by injection molding, for example, molten plastic into the upper and lower molds, with the peripheral edges of the separator film 20 held in advance in the molds. At this time, the part of the separator post 20a held in the mold is crushed, and if the battery is used in this state, the electrode plates located on both sides of the post 20a and the crushed separator membrane 20 of the post 20a will be damaged during operation. There was a problem in that the electrolyte stagnates in this area.

A characteristic feature of the present invention is that a separator membrane supporting protrusion is formed integrally with the separator frame 50 during injection molding of the separator frame 50, and this serves to compensate for the function of the crushed separator post 20a. , the gap between the separator membrane 20 and the electrode plate is maintained reliably, and the flow of the electrolyte is not obstructed.

In FIG. 1(A), the periphery of the separator film 20 held by the mold during injection molding of the separator frame 50 is indicated by a dotted line 100, and the separator post 20ab located on the dotted line 100 is compressed and damaged. It turns out.

For this reason, in the present invention, a protrusion 54 is formed integrally with the separator frame 50 during the injection molding to replace the crushed separator post 20ab. In the illustrated example, the separator support protrusion 54 is formed integrally with the rectification protrusion 52 for evenly flowing the electrolytic solution flowing from the manifold 50a throughout the reaction tank, and is formed over the entire inner peripheral edge of the separator frame 50. It is located at the tip of the protrusion 52. FIG. 2 shows this part enlarged.

Figure 1 (B) shows the III-IV cross section of Figure 1 (A),
Separator supporting protrusions 54 are formed over the entire width of the lower end of the separator frame 50 at regular intervals to replace the crushed separator posts 20ab.

FIG. 3 shows a state in which a separator frame 50 having separator supporting protrusions 54 is injection molded with the periphery of the separator film 20 being pressed and held by upper and lower molds.

Separator membrane 2 having separator posts 20a on both sides
The periphery of 0 is pressed and held by the upper and lower molds consisting of the upper mold 56 and the lower mold 58, and as a result, the separator post 20ab located in this portion is in a crushed state.

Therefore, both of the molds 56 and 58 corresponding to the mold parts of the separator membrane crushed by this mold have hollow parts 56a for injecting molten plastic.

58a is formed together with the hollow part for the separator frame 50, and in the embodiment, the rectifying protrusion 5 is formed in this hollow part 53.
2 and the separator supporting protrusion 54 are integrally formed.

The channel 60 serves to guide the electrolytic solution flowing from the electrolytic solution storage Ml through the manifold 50a of the separator frame 5° to the reaction vessels on both sides.

FIG. 4 shows a second embodiment of the present invention. This figure is a plan view of the separator film 20 held by the molds 56 and 58.

The characteristic feature of this embodiment is that the part of the mold that holds the separator film 20 is formed into a wave shape, and only the part where the separator supporting protrusion 54 is formed, that is, the part where the separator post 20ab to be crushed is formed, is molded. provides a distance 1 for stably and reliably holding the separator film 2o, and by recessing the other parts in a concave shape, the separator post 20ac is protected from compression damage, and the number of separator posts that are crushed is minimized. It's because it's configured.

According to this embodiment, it is possible to increase the number of separator posts that are left without being crushed by the mold, and it is possible to further stabilize the spacing between the electrodes and the separator film on both sides.

Further, the separator supporting protrusion 54 may have a vertically elongated isosceles triangular shape that meets the rectifying protrusion 52 as shown in FIG.

The separator support protrusions 54 are integrally injection molded with the separator frame 50 on the inner edges of the four sides of the separator frame 50, thereby preventing contact with electrode plates that are close to each other at a short distance on both sides when assembled into a battery. This can be prevented and the electrolyte solution can be kept flowing reliably and smoothly. In such a configuration, the separator supporting protrusion 5
4 is completely newly added and formed on the separator frame 50 side, so the separator post 2 of the separator film 20
Regardless of whether the dimensional accuracy of 0a is good or bad, it is possible to reliably maintain the distance between the separator film 20 and the electrode at the peripheral edge of the separator film 10.

[Effects of the Invention] As explained above, according to the present invention, a separator supporting protrusion that serves as a substitute for a separator post crushed by a mold during injection molding of a separator frame can be integrally injection molded with the separator frame. Since the structure is configured to do so, it is possible to easily prevent adhesion between the separator film and the electrode plate during battery operation at the damaged part of the separator post by simply changing the mold during injection molding, without affecting the dimensional accuracy of the separator film side. There is no need to attach special members for preventing adhesion during battery assembly, and manufacturing and assembly can be performed simply and easily.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a separator according to the present invention, FIG. 2 is a partially enlarged view of FIG. FIG. 5 is an explanatory diagram showing the second embodiment of the present invention, FIG. 5 is an explanatory diagram showing the third embodiment of the present invention, FIG. 6 is a configuration diagram of a conventional device, and FIG. 7 is a configuration diagram of a conventional separator. It is. 20...Separator film 20a...Separator post 50...Separator frame 52...Protrusion for rectification 54...Protrusion for supporting separator (A) 1 song (A)

Claims (1)

[Claims] (1) A plurality of cells are stacked, each consisting of a separator for self-discharge prevention and a positive electrode and a negative electrode placed on both sides of the separator, and an electrolytic solution is circulated and supplied independently to each electrode. In a liquid circulation type metal-halogen battery equipped with a reaction tank that performs a predetermined charging/discharging reaction, the separator includes a separator film formed on both sides of the post that holds both electrodes at a predetermined interval, and a periphery of the separator film. a separator frame that is injection molded to surround the separator film, and a plurality of protrusions located at the mold marks of the separator film crushed by an injection mold are integrally injection molded with the separator frame. Circulating metal-halogen battery.