JPH0660058U - Current collector for zinc-bromine battery - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a current collecting electrode for a zinc-bromine battery, in which “warpage” of the current collecting electrode due to thermal stress and external force is prevented and the mechanical strength of the current collecting electrode itself is increased. The purpose is to [Structure] The collector electrode 7 has a carbon plastic electrode 15 incorporated in a hole 17 formed by laminating a plurality of sheet-shaped insulating frame members 16b, and the insulating frame member 16b positioned on the rear surface a side. An overlapping portion 16c in which a part of the above is inserted along the surface of the carbon plastic electrode 15 is provided and integrally heat-welded. The overlapping portion 16c is formed by one or two sheet-shaped insulating frame members 16b located on the back surface side of the collecting electrode 7, and the thickness of the overlapping portion 16c is 1.0 to 2.0 mm. The length of the overlapping portion 16c is set to be in the range of 10 to 15 cm.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a collecting electrode which is a constituent member of an electrolyte circulating type laminated secondary battery, particularly a zinc-bromine battery.

[0002]

[Prior art]

 Zinc-bromine batteries are secondary batteries that use bromine as the positive electrode active material and zinc as the negative electrode active material. For example, this battery is used at night when power demand is low to solve the imbalance between day and night. It is used to store electricity and discharge it in the daytime.

Bromine generated on the positive electrode side at the time of charging reacts with the bromine complexing agent added to the electrolytic solution to be returned as an oily precipitate to the storage tank, and at the time of discharging it is pumped into the unit cell. It is sent and returned. The components of the electrolytic solution are a ZnBr ₂ aqueous solution, a salt such as NH ₄ Cl for reducing the resistance, and Pb, Sn, and quaternary ammonium salts for preventing dendrite on the negative electrode zinc side and promoting uniform electrodeposition. , With a bromine complexing agent. A separator is inserted between the positive electrode and the negative electrode to prevent self-discharge due to the bromine generated in the positive electrode diffusing into the negative electrode and reacting with zinc.

The chemical reaction of this zinc-bromine battery is

[0005]

[Chemical Formula 1] During charging: Positive electrode: 2Br ⁻ → Br ₂ + 2e ⁻ , Negative electrode: Zn ⁺⁺ + 2e ⁻ → Zn During discharging: Positive electrode: 2Br ⁻ ← Br ₂ + 2e ⁻ , Negative electrode: Zn ⁺⁺ + 2e ⁻ ← Zn It is represented by.

This zinc-bromine battery is mainly of a bipolar type and has a battery main body in which a plurality of cells (cells) are electrically stacked in series, an electrolytic solution storage tank, and a space between them. It consists of a pump and a piping system that circulates the electrolyte.

FIG. 9 is an exploded perspective view showing an example of a battery main body that constitutes the above zinc-bromine battery, in which an insulating frame 1b is arranged on the outer periphery of the electrode portion 1a of the bipolar plate-shaped intermediate electrode 1 having a rectangular flat plate shape. Similarly, in the separator plate 2 having a rectangular flat plate shape, the frame body 2 a is formed on the outer periphery of the separator 3. The separator plate 2 and, if necessary, the packing 4 and the spacer mesh 5 are stacked on the intermediate electrode 1 to form a single cell, and a plurality of the single cells are laminated to form a battery body.

A collector electrode 7 having a collector mesh 6, a pair of tightening end plates 8 and a stacking end plate 9 for pressing, which is located inside the collector electrodes 7, are provided at both ends of the stacked battery bodies. It is arranged. Then, a bolt (not shown) is passed between both the tightening end plates 8 and 8 to fasten the bolt to form a battery body integrally laminated and fixed.

In each unit cell of the battery main body configured as described above, a positive electrode manifold 10 formed at two upper and lower corners of the intermediate electrode 1 and the frame body 2 a of the separator plate 2, The electrolyte solution flows in and out from the negative electrode manifold 11 through the channels 12 and the microchannels 13 provided in the frame body 2a of the separator plate 2, respectively.

It has been confirmed that the zinc-bromine battery configured as described above has a battery efficiency of about 80% in a 50 KW class battery and an overall energy efficiency of about 70%.

As shown in FIGS. 10 and 11, the current collecting electrode 7 is formed on a sheet-shaped insulating frame member 16 a having a thickness of about 1 mm and having the same thickness as that of the insulating frame member 16 a, and the hole 17 is hollowed out. A plurality of insulating frame members 16b are laminated, and a carbon plastic electrode 15a having a thickness of about 1 mm, a brass current collecting mesh 6 and a carbon plastic electrode 15b having a thickness of about 3 mm are stacked in the hole 17. It is sequentially assembled in a sandwich form, and is integrally manufactured by using a die (not shown) based on heat pressing means under predetermined temperature and pressure conditions. Further, holes 18 for the manifold are opened in the insulating frame members 16a and 16b.

As conditions for the above heat press, for example, 150 ° C. and 55 kg / cm ² are adopted. The carbon plastic electrodes 15a and 15b are members formed by mixing polyethylene and carbon graphite, and have corrosion resistance against bromine.

The terminal piece 6a for extracting electric power, which is led out from the current collecting mesh 6, is led out to the outside through the slits 14 formed in the carbon plastic electrode 15a and the insulating frame member 16a, and is not shown in the drawing. It is connected to the electric bus bar. The arrow a in FIG. 11 indicates the back side and the arrow b indicates the liquid contact side.

[0014]

[Problems to be solved by the device]

 However, in the case of the current collecting electrode 7 used in such a conventional zinc-bromine battery, heat shrinkage occurs due to the difference in material between the back side a and the liquid contact side b (shown in FIG. 11) with respect to the electrolytic solution. It is unavoidable that there is a difference in the coefficient of thermal expansion or the coefficient of linear expansion, and especially when the temperature drops, cracks or “warps” occur in the insulating frame members 16a, 16b due to the difference in the thermal contraction rate, and the current collection. There is a fear that the flatness of the electrode may be deteriorated.

When the flatness of the collector electrode 7 is lowered, as described in FIG. 9 above, when the clamp end plates 8 and 8 constituting the battery body are tightened with bolts, the collector electrode 7 The liquid easily leaks from the interface of No. 7 and the stored electric power is lost. If the tightening force of the bolts is increased in order to eliminate this liquid leakage, there is a problem in that the stress concentrated on the interface easily causes the cracks in the constituent members. For this reason, a means for attaching a disc spring to the bolt to minimize the load change is usually used, but the problem that it cannot be said to be sufficient as a crack prevention measure remains.

The insulating frame members 16a and 16b are usually made of polyethylene resin mixed with talc, and have a smaller “elongation” at break than pure polyethylene resin. It is also a cause.

Furthermore, since the carbon plastic electrodes 15a and 15b are members formed by mixing polyethylene and carbon graphite as described above, they contain a large amount of inorganic filler, and therefore the electrodes themselves are said to be hard and brittle. It is characteristic, and it is also a factor that the crack easily occurs.

On the other hand, as one means for eliminating the above-mentioned “warpage” of the collector electrode 7 due to the difference in material in the thickness direction, the insulating frame member 16a shown in FIG. An attempt has also been made to arrange and weld the insulating frame member 16b and the carbon plastic electrodes 15a and 15b forming the electric electrode 7 in a substantially symmetrical manner in the thickness direction. By such means, it is possible to minimize the occurrence of “warpage” of the collector electrode due to heat shrinkage, but the welding interface between the insulating frame member 16b and the carbon plastic electrode 15b is on both the front and back sides. Since it is exposed, there is a possibility that a difficulty in strength may occur due to a decrease in rupture resistance and strain resistance due to the weld interface. Further, there is a problem that the mechanical strength of the rear surface a side of the current collecting electrode 7 becomes insufficient when the current collecting electrode 7 is assembled to the battery body.

The present invention has been made in view of the above points, and causes a warp phenomenon caused by thermal contraction of a current collecting electrode and a characteristic defect such as electrolyte leakage caused by the warp phenomenon. It is an object of the present invention to provide a current collecting electrode for a zinc-bromine battery that can eliminate the cause and increase the mechanical strength of the current collecting electrode itself to enhance the battery performance.

[0020]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention forms a single cell by stacking a separator plate on a rectangular flat plate-shaped intermediate electrode, and stacks a plurality of the single cells to form a battery main body. A sheet of zinc-bromine battery current collecting electrodes, in which a pair of current collecting electrodes and a tightening end plate are arranged at both ends, and the two tightening end plates are bolted together to be integrally laminated and fixed. The carbon plastic electrode was incorporated into the hole formed by laminating a plurality of insulating frame materials, and a part of the insulating frame material located on the back side was inserted along the surface of the carbon plastic electrode. A burlap portion is provided to provide a current-collecting electrode for a zinc-bromine battery integrally heat-welded.

The overlapped portion is formed by one or two sheet-shaped insulating frame members located on the back side of the collector electrode, and the thickness of the overlapped portion is 1.0 to 2.0 mm. The length of the overlapping part is set to be in the range of 10 to 15 cm.

[0022]

[Action]

 According to such a collecting electrode, since the carbon plastic electrode and the insulating frame material are arranged substantially symmetrically in the thickness direction, the occurrence of the “warp” of the collecting electrode due to thermal stress and external force is minimized. And, by providing an overlap part where a part of the insulating frame material located on the back side penetrates along the surface of the carbon plastic electrode, rupture resistance at the interface between the insulating frame material and the carbon plastic electrode is provided. Therefore, a collector electrode is obtained that satisfies the characteristics of strain resistance, pressure resistance against external pressure, bending characteristics and cyclic fatigue characteristics.

[0023]

【Example】

 An embodiment of the current collecting electrode of a zinc-bromine battery according to the present invention will be described in detail below with reference to the drawings, with the same components as those shown in FIG.

1 (A), (B) and (C) show a specific structure of the current collecting electrode 7 according to this embodiment, in which 15 is a carbon plastic electrode and 16b is a thickness of about 1 mm. It is a sheet-shaped insulating frame material. The carbon plastic electrode 15 is integrally incorporated in a hole 17 formed by laminating a plurality of the insulating frame members 16b and heat-welded.

In the example of FIG. 1 (A), a part of one insulating frame member 16b located on the rear surface a side is formed with an overlapping portion 16c in which the part of the insulating frame member 16b enters in the direction of the carbon plastic electrode 15. Further, in the example of FIG. 1 (B), the overlapping portion 16c is formed by the two insulating frame members 16b, 16b located on the rear surface a side. In the example of FIG. 1 (C), the overlapping portion 16c is formed on the rear surface a side. An overlapping portion 16c is formed by the three insulating frame members 16b, 16b, 16b located.

The carbon plastic electrode 15 and the insulating frame member 16b are manufactured in the same manner as the example described with reference to FIG. That is, by stacking a plurality of sheet-like insulating frame members 16b shown in FIG. 11, the carbon plastic electrode 15a having the above-mentioned overlapped portion in the hole 17 and the brass current collecting mesh 6 and the carbon plastic. The electrodes 15b are sequentially incorporated, and integrally molded by heat pressing means using a mold.

Therefore, in the example of FIG. 1 (A), the thickness of the overlapping portion 16c is approximately 1 mm, and in the example of FIG. 1 (B), the thickness of the overlapping portion 16c is approximately 2 mm, and the thickness of the overlapping portion 16c is approximately 2 mm. In the example, the thickness of the overlapping portion 16c is about 3 mm.

In order to evaluate various characteristics of the thus obtained three types of collector electrodes 7, the following items were measured.

(1) Measurement of amount of warpage In order to confirm whether or not “warpage” occurred in the obtained current collecting electrode 7, the three types of current collecting electrodes 7 obtained in this example were prepared using a large aluminum plate (about (3 mm thick), a 150 kg weight was applied for 24 hours, then left in a free state, and the size of the sled was measured at 12 points 1 to 12 shown in FIG. For the measurement, as shown in FIG. 3, the collecting electrode 7 was placed on the surface plate 20 and the measured value X by the hide gauge 21 was used.

FIG. 4 is a graph showing the relationship between the amount of warpage (mm) measured above and the number of days left to stand. (A) shows the case where the overlapping portion 16c is one, and (b) shows that the overlapping portion 16c has two. In the case of the number of sheets, (C) shows the case where the number of overlapping portions 16c is three.

From the graph of FIG. 4, the amount of warpage of the collecting electrode 7 is the smallest when the number of the overlapping portions 16c is one, and the amount of warpage is increased as the number of the overlapping portions 16c increases to two or three. Was found to be increasing.

On the other hand, FIG. 5 is a graph showing the relationship between the length of the overlapping portion 16c and the warp amount (mm). If the length of the overlapping portion 16c is in the range of 10 to 15 cm, the warp amount is Turned out to be few.

(2) Measurement of tightening strain The above warpage amount (mm) is measured when the laminated end plates are placed on both sides of the separator and the intermediate electrode that compose the zinc-bromine battery and the bolts are tightened with bolts. It is related to the amount of strain generation. Table 1 shows a case where the battery body is configured by using the collector electrode 7 in which the thickness of the overlapping portion 16c is 1.0 mm, 2.0 mm, and 3.0 mm, and uniform tightening is performed with a tightening torque of 300 kg-cm. The results of measuring the average warp amount (mm) and the generated strain (× 10 ⁻⁶ ) of the are shown.

[0034]

[Table 1]

From Table 1, it can be seen that the larger the average warp amount, the larger the generated strain. In particular, it is empirically known that the static strain due to tightening is within 4000 (× 10 ^-6 ) as a safe area. Therefore, of the three types of current collecting electrodes 7, the overlap portion 16c of It is understood that the thickness is 1.0 mm to 2.0 mm, and it is suitable that the number of sheets is one or two, and the number of three is not suitable.

(3) Measurement of Pressurization Characteristic by Air In the cell in the battery main body, a positive pressure to be pressed from the carbon plastic electrode side by the pressure of the pump and a carbon plastic generated when the electrolytic solution is drained are drawn. A negative pressure is applied. From the measurement results of the warp amount and the tightening strain, it was found that the number of the overlapping portions 16c should be one or two. Therefore, as shown in FIG. Two of them were attached and the pressurization characteristics by air were measured.

FIG. 7 is an air pressure-strain curve obtained by the above measurement. (A) shows the case where the number of the overlapping portions 16c is one, and (b) shows the case where the number of the overlapping portions 16c is two. Shown respectively. In the example of (a), the current collecting electrode 7 is broken by the negative pressure of the air pressure of 0.7 (kg / cm ² ) at the break point X in the figure, that is, at the interface between the insulating frame member 16b and the carbon plastic electrode 15. Although it broke, in the example of (b), the collector electrode 7 broke at the breaking point Y, that is, the portion closer to the inner side than the interface portion due to the negative pressure of the air pressure of 0.5 (kg / cm ² ). did. The breaking strain at that time was 15000 (× 10 ⁻⁶ ) in the example (a), whereas it was 9000 (× 10 ⁻⁶ ) in the example (b).

(4) Measurement of Bending Property by Test Piece In order to compare the strength of the interface between the insulating frame member 16c of each collector electrode 7 and the carbon plastic electrode 15, as shown in FIG. A large number of test pieces 7a having a width of 1.5 cm and a length of 15 cm were cut out from the test piece 7a, and the same gauges as the gauges 22 and 22 shown in FIG. 6 were attached to the test pieces 7a to perform a bending test. It was As a result, when the number of the overlapping portions 16c is one, all of the 10 pieces are broken at the breaking point X shown in FIG. 7, and when the number of the overlapping portions 16c is two, seven of the 10 pieces are broken. Was broken at the break point Y shown in FIG. This result almost agrees with the measurement result of the pressurization characteristic by air.

(5) Repeated Fatigue Test Using Test Piece Using the test piece 7a, tension and compression were continuously performed by a repeat tester until the test piece 7a broke, and the overlapping portion 16c In the case of one sheet, the sheet withstood repeated 20,000 times or more, but in the case of two sheets of overlapping portion 16c, the sheet was broken at 5000 times.

From the test results described above, of the three types of current collecting electrodes 7 according to the present embodiment, the number of the overlapping portions 16c is one or two, which is 1.0 to 2.0 mm in terms of thickness. It was found that the range of 10 to 15 cm is suitable, and the length of the overlapping portion 16c is 10 to 15 cm.

[0041]

[Effect of device]

 As described in detail above, the current collecting electrode according to the present invention has the carbon plastic electrode incorporated in the hole formed by laminating a plurality of sheet-shaped insulating frame members, and the insulating frame positioned on the back side is The carbon plastic electrode and the insulating frame material are arranged substantially symmetrically in the thickness direction by providing an overlap part in which a part of the material has entered along the surface of the carbon plastic electrode and integrally heat welding. As a result, the occurrence of “warpage” or cracks in the current collector electrode due to thermal stress is minimized, and the flatness of the current collector electrode is maintained well, which prevents liquid leakage from the battery body. It is not necessary to unnecessarily increase the tightening force of the bolts in order to eliminate it, and the effect that the assemblability is enhanced is obtained.

Further, by providing the overlapping portion, the welding interface between the insulating frame member and the carbon plastic electrode is not exposed on both the front and back of the current collecting electrode, and the insulating frame member and the carbon plastic electrode are not exposed. It is possible to obtain a current-collecting electrode that has improved rupture resistance at the interface and that also satisfies the strain resistance, pressure resistance against external pressure, bending characteristics, and repeated fatigue characteristics.

Therefore, according to the present invention, the warpage phenomenon caused by the thermal contraction of the current collecting electrode and the cause of the characteristic failure such as the electrolyte leakage due to the warpage phenomenon are eliminated and the mechanical strength is eliminated. The present invention provides a current collecting electrode for a zinc-bromine battery, which has a high efficiency.

[Brief description of drawings]

1A, 1B, and 1C are cross-sectional views of a main part for schematically explaining a specific embodiment of the present invention.

FIG. 2 is a plan view showing measurement points of “sledding” in the present embodiment.

FIG. 3 is a schematic side view of a gauge for measuring the “warpage”.

FIG. 4 is a graph showing the correlation between the amount of warpage and the number of days left for each of the examples shown in FIG.

FIG. 5 is a graph showing the correlation between the “warpage amount” and the length of the overlapping portion in the above embodiment.

FIG. 6 is a schematic view showing a mounting position of a gauge at the time of measuring a pressurizing characteristic of a collector electrode by air.

FIG. 7 shows the correlation between the air pressure on the collector electrode and the strain amount,
FIG. 5 is a schematic view showing the breakage position of the current collecting electrode in contrast to FIG.

FIG. 8 is a plan view showing a test piece for measuring bending strength in this example.

FIG. 9 is an exploded perspective view of essential parts showing a battery body of a zinc-bromine battery.

FIG. 10 is a plan view showing a structural example of a conventional collector electrode.

FIG. 11 is an exploded cross-sectional view of a main part showing an example of a conventional assembling structure of a collector electrode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Intermediate electrode 1a ... Electrode part 1b ... Frame 3 ... Separator 6 ... Current collecting mesh 6a ... Terminal piece 7 ... Current collecting electrode 7a ... Test piece 8 ... Clamping end plate 9 ... Laminated end plate 10 ... Positive electrode manifold 11 ... Negative electrode manifold 12 ... Channel 13 ... Micro channel 15 ... Carbon plastic electrode 16b ... Insulating frame material 16c ... Overlap part 17 ... Hole part 20 ... Surface plate 21 ... Hide gauge

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuo Ando 2-1-1-17 Osaki, Shinagawa-ku, Tokyo Stock Company Inside the Shameidensha (72) Inventor Yasuharu Namiki 2-1-1-17 Osaki, Shinagawa-ku, Tokyo Stock Association Shameidensha

Claims (3)

[Scope of utility model registration request] 1. A rectangular flat plate-shaped intermediate electrode is laminated with a separator plate to form a single cell, and a plurality of the single cells are laminated to form a battery main body, and a pair of collectors are provided at both ends of the battery main body. A collector electrode for a zinc-bromine battery, in which a current-carrying electrode and a tightening end plate are arranged, and the two tightening end plates are bolted together so that they are integrally laminated and fixed. The carbon plastic electrode is incorporated in the hole formed by stacking the sheets, and an overlapping part is provided by inserting a part of the insulating frame material located on the back side along the surface of the carbon plastic electrode to provide an integrated structure. A current collecting electrode for a zinc-bromine battery, characterized by being heat-welded to. 2. The current collecting electrode for a zinc-bromine battery according to claim 1, wherein the overlapping portion is formed by one or two sheet-shaped insulating frame members located on the back surface side of the current collecting electrode. 3. The thickness of the overlap portion is 1.0 m
m-2.0mm, the length of the overlap is 10-15
The current collecting electrode of the zinc-bromine battery according to claim 1, which is in a range of cm.