JP2744189B2 - Bipolar type metal-hydrogen secondary battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bipolar metal-hydrogen secondary battery, and more particularly to a bipolar nickel-hydrogen secondary battery having an improved reaction gas supply mechanism to an anode.

[0002]

2. Description of the Related Art Nickel-hydrogen secondary batteries are based on individual Pr.
essure Vessel (IPV) type cell, Com
monPressure Vessel (CPV) type cells and Bipolar Batteries (bipolar type batteries). In all of these sealed nickel-hydrogen secondary batteries, the entire electrode stack is generally housed in a cylindrical pressure-resistant container. The internal hydrogen gas is consumed at the time of discharging, and the hydrogen gas is generated at the time of charging and is circulated. Is possible.

[0003] Among the above nickel-hydrogen secondary batteries,
For high power systems that require active thermal control, bipolar nickel-hydrogen rechargeable batteries incorporating fuel cell technology are advantageous. This battery can be reduced by 25% in weight, 50% in volume, and 50 to 70% in cost when assembled in the same class by IPV type. As such a bipolar nickel-hydrogen secondary battery, one having a structure shown in FIG. 3 (here, only a laminated structure is shown) is conventionally known. That is, reference numeral 1 in the figure denotes a cathode formed of a nickel electrode. Reference numeral 2 in the figure denotes an anode composed of a porous catalyst layer provided on one side with a conductive metal screen 3 composed of a nickel mesh. The metal screen 3 is adhered to the anode 2 made of the porous catalyst layer via a hydrophobic material such as a fluorinated ethylene-propylene copolymer (FEP). A separator 4 holding a liquid electrolyte is interposed between the cathode 1 and the anode 2 (the side opposite to the nickel mesh 3). A metal spacer 5 having air permeability and conductivity is electrically connected to the anode 2 on the side of the mesh body 3. The metal spacer 5 has a shape in which a plurality of holes are formed in a flexible and elastic corrugated metal sheet made of, for example, nickel or stainless steel. The cathode 1, anode 2, separator 4, and metal spacer 5 constitute a unit cell 6. The plurality of unit cells 6 are stacked via a nonporous conductive plate 7. The plate 7 has an area larger than that of the unit cell 6, and the periphery thereof extends to the outside from the periphery of the unit cell 6. A hollow ring-shaped plate 8 is interposed between the anode 2 and the metal spacer 5,
A hydrogen gas supplied through a gasket passage described later can be supplied to the metal spacer 5. A hollow ring-shaped gasket 9 is provided around the unit cells 6 so as to cover the extending portions of the plates 7 and 8, respectively, to seal the unit cells 6 between the plates 7. The gasket 9 is made of a suitable material such as rubber or an electrolyte-resistant plastic such as an epoxy resin-glass laminate, and has vertically stacked contact surfaces sealed with an adhesive. In the gasket 9 corresponding to the metal spacer 5 of the unit cell 6, a passage 10 for supplying hydrogen gas to the metal spacer 5 is opened in the horizontal direction.

However, in the above-described bipolar nickel-hydrogen secondary battery having the laminated structure shown in FIG. 3, the conductive metal screen 3 and the nonporous plate 7 are provided between the conductive metal screen 3 and the non-porous plate 7 in order to supply the anode 2 with a reactive gas. Because of the structure in which the air-permeable and conductive metal spacers 5 are provided, there are the following problems. That is, since pressure is applied to the contact between the corrugated portion of the metal spacer 5 and the anode 2 when the batteries are stacked, the anode 2 is deformed and further damaged. In addition, unevenness in the tightening of the laminate occurs due to the unevenness in the thickness and the flatness of the metal spacers 5, resulting in poor contact between components. As a result, the self-discharge increases due to the deterioration of the polarization characteristics of the anode 2 and the leakage of hydrogen gas to the cathode 2 side, the internal impedance increases, and the cell characteristics deteriorate due to these. As a result, the cycle life of the entire battery decreases. There was a problem to invite.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and it is possible to suppress the deformation of the anode at the time of lamination and provide a reaction gas supply layer having a uniform thickness and flatness. It is intended to provide a bipolar nickel-hydrogen secondary battery provided with such a battery.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a unit cell is constructed in which bipolar electrodes of a cathode and an anode are adjacent to each other via a separator containing a liquid electrolyte, and a reaction gas supply member is arranged on the anode side. Further, in a bipolar metal-hydrogen secondary battery having a structure in which a plurality of the unit cells are stacked with a non-porous conductive plate interposed therebetween and the periphery thereof is sealed with a gasket member, the reaction gas supply member is repelled in the void. A porous anode formed of a water-treated three-dimensional mesh-like metal porous body made of a metal porous body and containing at least a catalyst on one surface of the reaction gas supply layer is formed by reacting at least the catalyst in the anode with the catalyst. A bipolar metal-hydrogen secondary battery, which is provided integrally so as to be filled in a porous body of a gas supply layer.

[0007] As the three-dimensional mesh-like metal porous body used for the reaction gas supply layer, for example, a sponge-like metal porous body having a porosity of 90% or more can be used. Specifically, Celmet (porosity: 9) manufactured by Sumitomo Electric Industries, Ltd.
About 5 ± 3%) can be used. In addition, by using this sponge-like porous body, the reaction gas supply to the porous body can be made more uniform and the reaction gas supply to the anode can be made more uniform than in a two-dimensional porous body. Can be improved.

Next, the bipolar metal according to the present invention
The laminated structure of the hydrogen secondary battery will be described in detail with reference to FIG. In the figure, reference numeral 11 denotes a cathode made of a nickel electrode.
Reference numeral 12 in the drawing denotes an anode comprising a porous catalyst layer containing at least a catalyst and having a larger area than the cathode 11. Between the cathode 11 and the anode 12, a separator 13 having a substantially similar area as the cathode 11 holding the liquid electrolyte is interposed. The anode 12 opposite to the separator 13 is integrally provided with a reactive gas supply layer 14 made of a three-dimensional mesh-like metal porous body and having a water-repellent treatment in the gap. Specifically, the anode 12 made of the porous catalyst layer is filled on one surface of the reaction gas supply layer 14 made of a porous metal body with at least the catalyst in the anode 12 filled in the porous body of the reaction gas supply layer 14. The porous body portion except for the filling portion 15 is used as a reaction gas supply layer. The reaction gas supply layer 14 is provided on the anode 12
Doubles as a current collector. The cathode 11, the anode 12, the separator 13, and the reaction gas supply layer 14 integrated with the anode 12 constitute a unit cell 16. The unit cell 16 includes a non-porous conductive plate 17.
Are laminated. The area of the plate 17 is slightly smaller than that of the anode 12. A hollow ring-shaped gasket 1 is provided around the anode 12 and the conductive plate 17 on the reactive gas supply layer 14 side.
The anode 12, the cathode 11, and the separator 13, which constitute each unit cell 16 between the plates 17, are hermetically sealed by respectively sealing 8 through a seal portion 19. The gasket 18 is formed from rubber, an electrolyte resistant plastic such as an epoxy resin-glass laminate. The laminate having such a structure is housed in a pressure vessel (not shown), and the reaction gas is supplied from a reaction gas supply pipe connected to the pressure vessel, so that the anode passes through the reaction gas supply layer 14 exposed on the side surface of the laminate. 12
Is supplied with a reaction gas.

[0009]

According to the present invention, the reactive gas supply member is formed by a reactive gas supply layer made of a three-dimensional mesh-like porous metal body having a water-repellent inside of the gap, and at least one surface of the reactive gas supply layer is provided on the one side of the reactive gas supply layer. By integrally providing a porous anode containing a catalyst so that at least the catalyst in the anode is filled in the porous body of the reaction gas supply layer,
The following operations are performed.

That is, unlike the conventional corrugated metal spacer, the surface of the reaction gas supply layer is flat and the anode is provided integrally with the reaction gas supply layer. The application of local pressure from the supply layer to the anode can be prevented, and deformation, breakage, and the like of the anode can be prevented. In addition, since the reaction gas supply layer having the above-described structure has a uniform thickness and flatness, it is possible to uniformize the tightening between the constituent members of the unit cell and the non-porous conductive plate at the time of lamination, and to reduce the gap between the members. The contact property can be improved.
Moreover, since the inside of the voids of the porous body constituting the reaction gas supply layer is water-repellent, water generated during the reaction of the hydrogen gas at the anode during battery discharge forms a liquid film on the interface between them. Instead, they can be dispersed as particles and the reaction gas can be smoothly supplied to the anode. Further, by integrally providing the anode so that at least the catalyst therein is filled in the porous body of the reaction gas supply layer, the anode and the reaction gas supply layer also function as a current collector of the anode. Contact resistance can also be reduced.

Therefore, since the polarization characteristics of the anode, the leakage of hydrogen gas to the cathode, and the increase in internal impedance can be improved, a bipolar metal-hydrogen secondary battery having excellent cell characteristics and a long cycle life can be provided. Obtainable.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an example in which the present invention is applied to a bipolar type nickel-hydrogen secondary battery using an alkaline electrolyte will be described. Example 1 Water was added about 10 times the dispersion to 60 parts by weight of carbon black added with 10 wt% of platinum as catalyst-supporting carbon particles and 40 parts by weight of a dispersion of polytetrafluoroethylene (PTFE) as a hydrophobic binder. After adding and mixing, the mixture was filtered and dried to prepare a homogeneous mixture of the catalyst-supporting carbon particles and the hydrophobic admixture. Subsequently, the mixture was uniformly mixed, kneaded to form the PTFE into fibers, and then formed into a sheet with a roller to produce a sheet-like porous catalyst layer.

On the other hand, after immersion in a PTFE dispersion having a concentration of 5% and heat treatment at 340 ° C., a porosity of 96%, a pore diameter of 0.4 to 2.0 mm, and a thickness of 0.4 were obtained.
mm sponge-like nickel porous body was produced.

Next, the sheet-like porous catalyst layer was pressure-bonded and integrated on one side of the porous body with a roller. As shown in FIG. 2, the structural material integrated in this manner includes an anode 12 made of a sheet-like porous catalyst layer, a reaction gas supply layer 14 in which voids have been subjected to a water-repellent treatment, and a porous material of the reaction gas supply layer 14. One side of the body is composed of a catalyst-carrying carbon particle in the anode 12 and a filling portion 15 filled with hydrophobic binder particles. Thereafter, the integrated structural material is heated to 330 ° C. in a nitrogen gas atmosphere.
Was heat-treated.

The above-described bipolar nickel-hydrogen secondary battery shown in FIG. 1 was assembled using the integrated structure material provided with the obtained anode 12 and the reaction gas supply layer 14 in which the voids were subjected to a water-repellent treatment. Note that as the separator 13, asbestos containing an alkaline electrolyte was used.

Comparative Example A sheet-like porous catalyst layer similar to that of Example 1 was prepared with a wire diameter of 0.20.
After being press-bonded to a 50 mm mesh nickel mesh body with a roller, heat treatment was performed at 330 ° C. in a nitrogen gas atmosphere to produce an anode.

Using the obtained anode, FIG.
Was assembled (using a corrugated metal spacer). The separator 4
Asbestos containing an alkaline electrolyte was used.

A charge / discharge cycle test was performed on the bipolar nickel-hydrogen secondary batteries of Example 1 and Comparative Example. As a result, a characteristic diagram shown in FIG. 4 was obtained. This exam is
Charge 1C, discharge 0.5C, discharge depth 30%, C / D ratio =
The test was performed under the conditions of 1.05 and a temperature of 20 ° C. In addition, A in FIG. 4 shows a characteristic line of the battery of Example 1 and B shows a characteristic line of the battery of Comparative Example.

As is apparent from FIG. 4, the battery of Example 1 has good characteristics with a high discharge voltage and little deterioration in characteristics due to charge / discharge cycles. Further, the battery of Example 1 was able to achieve a weight reduction of 10% as compared with the battery of the comparative example.

Example 2 A sheet-like porous catalyst layer prepared in the same manner as in Example 1 was pressure-bonded and integrated with a nickel mesh of 0.20 mm in wire diameter and 50 mesh as a current collector using a roller. An anode was produced by heat treatment at 330 ° C. in a gas atmosphere.

On the other hand, a sponge having a porosity of 96%, a pore diameter of 0.4 to 2.0 mm, and a thickness of 0.4 mm, which was immersed in a 5% PTFE dispersion and then heat-treated at 340 ° C. A reaction gas supply layer made of a nickel porous body was prepared, and the above-mentioned bipolar nickel-hydrogen secondary battery shown in FIG. 1 was used using the anode and the reaction gas supply layer. (Which is not filled in the reaction gas supply layer and is merely arranged in a stacked state). Note that as the separator 13, asbestos containing an alkaline electrolyte was used.

When a charge / discharge cycle test was performed on the bipolar nickel-hydrogen secondary battery of Example 2 under the same conditions as in Example 1, it was found that the discharge voltage was high and the characteristic deterioration due to the charge / discharge cycle was small. It was confirmed that it exhibited characteristics.

[0023]

As described in detail above, according to the present invention, it is possible to suppress the deformation of the anode at the time of lamination, to provide a reaction gas supply layer having a uniform thickness and flatness, and to have excellent cell characteristics. A bipolar nickel-hydrogen secondary battery having a long cycle life can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a stacked structure of a bipolar nickel-hydrogen secondary battery according to the present invention.

FIG. 2 is a cross-sectional view showing an integrated structural material provided with an anode and a reaction gas supply layer in which a void portion has been subjected to a water-repellent treatment in Example 1.

FIG. 3 is a cross-sectional view showing a stacked structure of a conventional bipolar nickel-hydrogen secondary battery.

FIG. 4 shows bipolar nickel of Example 1 and Comparative Example.
FIG. 4 is a characteristic diagram showing a charge / discharge cycle in a hydrogen secondary battery.

[Explanation of symbols]

11 ... cathode, 12 ... anode, 13 ... separator,
14: reactive gas supply layer 16: unit cell, 17: conductive metal plate, 18 ...
gasket.

Continued on the front page (72) Inventor Nobukazu Suzuki 1 Toshiba-cho, Komukai, Koyuki-ku, Kawasaki-shi, Kanagawa Prefecture (72) Inventor Tamotsu Jojo 1-Toshiba-cho, Komukai-shi, Kochi-ku, Kawasaki-shi, Kanagawa Toshiba Research and Development Center Co., Ltd. (56) References JP-A-63-228569 (JP, A)

Claims (1)

(57) [Claims] 1. A unit cell comprising a bipolar electrode of a cathode and an anode adjacent to each other via a separator containing a liquid electrolyte, and a reaction gas supply member disposed on the anode side to form a unit cell. In a bipolar metal-hydrogen secondary battery having a structure in which a plurality of porous conductive plates are interposed and the periphery of which is sealed with a gasket member, the reaction gas supply member is formed in a three-dimensional mesh having a water-repellent inside of a void. A porous anode including at least a catalyst on one surface of the reaction gas supply layer, wherein at least the catalyst in the anode is in the porous body of the reaction gas supply layer. A bipolar metal-hydrogen secondary battery, which is provided integrally so as to be filled.