JP3039055B2 - Manufacturing method of cylindrical air cell and cylindrical air electrode - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical air battery using oxygen as an active material and a method for manufacturing a cylindrical air electrode.

[0002]

2. Description of the Related Art Conventionally, a cylindrical air electrode is made of a polytetrafluoroethylene (hereinafter referred to as PTFE) having a gas-permeable ability and having a water-repellent film, a nickel net, an expanded current collector, or other conductive current-collecting sheet, and various metals. An electrode having a three-layer structure formed by stacking porous catalyst sheets made of a mixture of oxide, activated carbon, and PTFE dispersion and pressing the whole is pressed into a curved cylindrical shape. It is constituted by bonding both ends with a synthetic rubber or epoxy resin adhesive. For example, an oxygen gas permeable sheet made of PTFE, polytetrafluoroethylene-hexafluoropropylene copolymer or the like as a water-repellent layer, and activated carbon powder carrying platinum, palladium, silver, manganese dioxide or the like as a porous catalyst layer A sheet of a conductive porous body obtained by binding
Using a metal net of nickel, expanded metal, or the like as the current collector layer, a water repellent layer, a porous catalyst layer, and a current collector layer are laminated in this order, and a three-layer structure is formed by pressure bonding. The electrode is curved so that the current collector layer is on the inside, and a part of both ends of the sheet is overlapped to form a cylindrical shape. Next, the water-repellent layer and the porous catalyst layer in the overlapped portion were removed, and the exposed current collector layer was welded by a welding method such as spot welding or beam welding. After filling the current collector layer into a cylindrical shape by spot welding or the like, a method of filling the resin and repairing the solution in a liquid-tight manner (JP-A-58-75773), and placing the catalyst layer sheet on both ends of the cylinder outside the cylinder. There is a method of slightly overlapping and winding, and furthermore, slightly overlapping the water-repellent sheets at both ends, winding and press-bonding them to integrate them (Japanese Patent Laid-Open No. 58-198862).

[0003]

In any of the above methods, the joints must be bonded in a liquid-tight manner with an adhesive or heat welding. However, since the water-repellent layer is mainly composed of fluororesin, The bonding effect is extremely weak. When such a cylindrical air electrode is used as a positive electrode, and a negative electrode (for example, zinc) is filled inside the separator through a separator, the zinc is changed to zinc oxide or the like as the battery discharge reaction proceeds. As a result, the joint expands and the electrolyte leaks from the joint, resulting in a decrease in battery performance.

An object of the present invention is to solve such problems and to provide a method for manufacturing a cylindrical air battery and a cylindrical air electrode which are excellent in liquid leakage resistance and discharge performance.

[0005]

In order to solve these problems, the present invention provides a catalyst layer, a metal current collector layer, a gas diffusion layer, and an oxygen-selective permeable membrane having an oxygen gas reducing ability from the inside to the outside. Production of a cylindrical air battery and a cylindrical air electrode, characterized in that a cylindrical air electrode having a four-layer structure comprising layers is used, and the gas diffusion layer has a completely liquid-tight cylindrical side surface without a joint. I found the law.

That is, the catalyst layer is directed outward from the inside,
A cylindrical air electrode having a four-layer structure including a metal current collector layer, a gas diffusion layer, and an oxygen-selective permeable membrane layer. First, a catalyst layer sheet having an oxygen gas reducing ability is placed outside a cylindrical jig. A wound catalyst layer is formed, and then a current collector layer is formed by weaving a metal wire on the outer surface of the column. A gas diffusion layer is formed on the outside by extrusion molding. Further, a cylindrical air electrode is produced by a method of manufacturing a cylinder having a four-layered structure by winding an oxygen-selective permeable membrane around the outermost periphery and then extracting a cylindrical jig.

[0007]

When producing a cylindrical air electrode, a conventional method has been designed to prevent liquid leakage from the joint by bending the flat electrode and devising the joint in any method. However, the degree of leakage resistance of the joints is not sufficient, though varying in degree. This can be considered as inevitable as long as the water-repellent portion has a joint, and eliminating the joint is an important technique. As in the present invention, a mixture obtained by mixing carbon black and a fluororesin, adding water or an organic solvent containing a surfactant, and kneading the mixture was formed into a cylindrical shape without a joint by extrusion molding using a circular slit. Thereafter, by heating to remove the surfactant, this layer can be a water-repellent layer having no joint. That is, it is possible to prevent the electrolyte from leaking from the inside to the outside of the cylindrical electrode through the joint portion, and to dramatically improve the liquid leakage resistance of the cylindrical air battery having this electrode as a positive electrode. . In addition, such a gas diffusion layer is newly provided,
With the four-layer structure, oxygen can be supplied to the entire catalyst layer, and the battery performance is improved as compared with the conventional three-layer structure.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the drawings according to specific embodiments.

FIG. 1 is a half sectional view of an AA zinc battery using the cylindrical air electrode of the present invention. In the figure, what is encircled and enlarged is a four-layer cylindrical air electrode (X) according to the present invention, 1 is a porous catalyst layer, and 2 is a nickel-plated stainless steel wire (metal current collector). Layers), 3 is a gas diffusion layer, and 4 is an oxygen-selective permeable membrane layer. Reference numeral 5 denotes a sealant for preventing the electrolyte from flowing into the gap between the oxygen-selective permeable membrane layer and the gas diffusion layer, reference numeral 6 denotes a separator, and reference numeral 7 denotes a gelled zinc negative electrode. The gelled zinc negative electrode was prepared as follows. 40
3% by weight of sodium polyacrylate and 1% by weight of carboxymethylcellulose are added to a 3% by weight aqueous solution of potassium hydroxide (containing 3% by weight of ZnO) to gel. next,
A zinc alloy powder having a weight ratio twice that of the gel electrolyte was added and mixed to obtain a gel zinc negative electrode. 8 is air diffusion paper,
9 is a positive electrode can and 10 is an insulating tube. 11 is an air intake hole, 12 is a hermetic seal to be peeled off before using the battery, 13 is a positive electrode cap, and 14 is a plate. 15,1
Reference numeral 6 denotes a metal cap, which has a cylindrical air electrode sandwiched between 15 and 16 to be pressed and pressed, and is spot-welded to the positive electrode can to collect current. 17 is an organic sealant, 18 is a resin sealing body, 19 is a negative electrode terminal cap, and 20 is a negative electrode current collector.

Next, a method for manufacturing a four-layer cylindrical air electrode according to the present invention will be described. FIG. 2 shows a schematic diagram of the manufacturing process. 1 in the figure is a porous catalyst layer having an oxygen reducing ability. In this experiment, manganese oxide, activated carbon, acetylene black, and fluorine resin powder
After sufficiently mixing at a ratio of 30% by weight, 30% by weight, 15% by weight and 15% by weight, the mixture was formed into a sheet by hot pressing at 360 ° C. Manganese oxide is γ-
MnOOH that had been heat-treated at 400 ° C. in a nitrogen stream was used. Reference numeral 2 denotes a nickel-plated stainless steel wire. After winding the porous catalyst sheet formed by the above-described method around a cylindrical jig 21 (Step 1), a nickel-plated stainless steel wire is woven outside (Step 2). The machine used at this time is a knitting machine that is commonly used when producing a covered electric wire, and a similar machine was adjusted and used in this experiment. Reference numeral 3 denotes a gas diffusion layer made of acetylene black and a fluororesin. This was made into a seamless cylindrical shape by extrusion molding, but was produced by the following procedure. Water 3 for 10 kg of acetylene black
00 kg, surfactant (polyethylene octyl phenyl ether manufactured by Kanto Chemical Co., Ltd .: trade name: Triton X-100) 2 k
g, 15 kg of fluororesin powder, mixed, stirred, filtered,
After drying (100 ° C.) and pulverizing steps, a highly dispersed mixed powder of acetylene black and a fluororesin is obtained. 10 kg of solvent naphtha is added to 5 kg of the mixed powder and kneaded to obtain a rubbery black. Next, while passing the inside of the circular slit through 1 and 2 produced by the above method,
The rubbery black was extruded from a circular slit so as to cover 1 and 2, thereby obtaining a cylindrical shape. As a result,
A cylindrical air electrode having a three-layer structure of two and three is obtained (step 3). However, at this time, since the surfactant (Triton X-100) remains, the water repellency of the gas diffusion layer 3 is poor. Therefore, before forming the oxygen-selective permeable membrane, it is heat-treated at 290 ° C. to remove the surfactant (Step 4). Although the porous catalyst layer also contains a fluororesin, the layer does not have complete water repellency due to a small mixing ratio. That is, in the case of a battery, the electrolytic solution permeates into one porous catalyst layer but is stopped inside the third water-repellent gas diffusion layer. In addition, since the gas diffusion layer 3 does not have a joint which has been a problem, the leakage resistance of the electrolytic solution can be significantly improved. Finally, a 150 μm-thick oxygen-selective permeable membrane made of fluororesin is slightly overlapped and wound to form 4 (Step 5). Through the above steps, a cylindrical air electrode having a four-layer structure is completed.

An AA type zinc-air battery using a cylindrical air electrode having a gas diffusion layer (water repellency) having a four-layer structure and no junction, manufactured by the above method, and a conventional three-layer structure having a junction The discharge performance and leakage resistance of the battery using the cylindrical air electrode having the above characteristics were compared. The results are shown in (Table 1).

[0012]

[Table 1]

[0013] Battery No. 1 in the table was prepared by the above method.
AA type zinc-air battery using a cylindrical air electrode with a gas diffusion layer with a layered structure and no joint. No. 2 uses a cylindrical air electrode with a four-layer structure and only the gas diffusion layer part. Unlike No. 1, the material is the same as that of No. 1, and this is a battery in which a gas diffusion layer is formed by forming this into a sheet shape, and stacking and pressing both ends. That is, the gas diffusion layer of the No. 1 battery of the present invention has a joint. No. 3 is a battery using a conventional three-layer air electrode, and was manufactured as follows.
Water-repellent layer composed of a fluororesin porous film, porous catalyst layer (the same porous catalyst sheet as that of the battery of the present invention), current collector layer (a net made of a nickel-plated stainless steel wire) Are laminated in this order and crimped to form a cylindrical shape by curving the current collector layer inside and partially overlapping both ends of the sheet. Next, the water-repellent layer and the porous catalyst layer in the overlapped portion are removed, and the exposed current collector layer is spot-welded, and the welded portion is filled with a fluororesin to perform liquid-tight repair. This was used as a positive electrode, and the remaining battery configuration was the same as that of the present invention. In No. 4, the current collector layer was previously joined in a cylindrical shape using spot welding, and then the catalyst layer sheet was wound around the outside of the cylinder with the both ends slightly overlapped, and furthermore, was composed of a fluororesin porous membrane. A cylindrical air electrode is produced by a method in which the water-repellent layer is slightly overlapped at both ends, wound, and heat-pressed to be integrated. The battery configuration is the same as that of the present invention after using this as a positive electrode. Regarding the battery discharge performance, a comparative value when the discharge time of No. 3 battery was set to 100 is shown for comparison. Regarding the leak resistance, the batteries discharged at each discharge load were stored at 20 ° C. for one month, and the number of batteries leaking is shown in the table. The n number at this time is 10. In the discharge characteristics, No. 3 and No.
No. 4 of the present invention has almost the same performance,
For batteries, 46% at 1Ω load discharge and 22% at 10Ω load discharge
%, The discharge time increased by 11% at 75Ω load discharge.
Also, in the No. 2 battery, the discharge time increases at almost the same rate. This is because a new gas diffusion layer is provided.
It is thought that the discharge performance was improved by supplying oxygen gas throughout the reaction layer through the gas diffusion layer by adopting the layer structure. No. 3 and No. 3
In No. 4, 50% or more of the batteries leaked, whereas No. 1 battery of the present invention did not have any leaky batteries. This is No.
In the No. 3 and No. 4 batteries, the volume of zinc expanded due to the discharge and the bonding strength was weakened, and the leak occurred from there. It is probable that it was prevented. No.
In the No. 2 battery, the number of leaked batteries was smaller than that of No. 3 and No. 4, but the leak resistance was slightly inferior due to the presence of the joint in the gas diffusion layer. When the porous catalyst layer of the present invention is used as a seamless cylindrical shape by extrusion molding, the discharge performance and liquid leakage resistance are equal to those of No. 1, and the manufacturing process can be simplified. In this example, a stainless steel-coated nickel-coated wire was used as the metal current collector, but the same applies to a stainless wire and a nickel wire.

[0014]

As apparent from the above description, according to the present invention, a four-layer structure comprising a catalyst layer, a metal current collector layer, a gas diffusion layer and an oxygen-selective permeable membrane layer is provided from the inside to the outside. By using a cylindrical air electrode and a cylindrical air electrode having a structure in which a gas diffusion layer has a completely liquid-tight cylindrical side surface without a joint, a cylindrical air battery having excellent discharge performance and leakage resistance can be provided.

[Brief description of the drawings]

FIG. 1A is a half sectional view of a cylindrical air battery according to an embodiment of the present invention. FIG. 1B is an enlarged view of a main part of the battery of the present invention.

FIG. 2 is a manufacturing process diagram of a cylindrical air electrode according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Porous catalyst layer 2 Nickel-plated stainless steel wire (metal current collector layer) 3 Gas diffusion layer 4 Oxygen-selective permeable membrane layer X 4-layer cylindrical air electrode 6 Separator 7 Gel zinc negative electrode 9 Positive electrode can 11 Air intake

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoshiaki Nitta 1006 Kazuma Kadoma, Kadoma City, Osaka Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A-61-290658 (JP, A) JP-A-2 -257577 (JP, A) JP-A-59-205168 (JP, A) JP-A-58-198862 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01M 12/06- 12/08 H01M 4/86-4/88

Claims (6)

(57) [Claims] 1. A negative electrode mainly composed of zinc, a separator,
A catalyst layer having oxygen gas reducing ability from the inside to the outside,
Metal collector layer, gas diffusion layer and oxygen-selective permeable membrane layer
A cylindrical air battery comprising a cylindrical air electrode having a four-layer structure , an air diffusion paper, and a positive electrode can having an air intake hole, wherein at least the gas diffusion of the cylindrical air electrode having the four-layer structure is performed.
The layer is made of a single piece that has been previously molded into a cylindrical shape.
A cylindrical air battery that is not completely liquid-tight and has a structure with cylindrical sides . 2. The cylindrical air battery according to claim 1, wherein the gas diffusion layer is a porous body mainly composed of carbon black and a fluororesin. 3. The cylindrical air battery according to claim 1, wherein the catalyst layer is made of a catalyst mixture containing at least one of manganese oxide, activated carbon, carbon black and fluororesin. 4. The cylindrical air battery according to claim 1, wherein the metal current collector layer comprises a wire including at least one of a stainless wire, a nickel wire, and a nickel-plated stainless steel wire. 5. A cylindrical air electrode having a four-layer structure comprising a catalyst layer, a metal current collector layer, a gas diffusion layer and an oxygen-selective permeable membrane layer from the inside to the outside, wherein the catalyst sheet has a cylindrical shape. A wound catalyst layer is formed on the outside of the jig, a current collector layer is formed by weaving a metal wire on the outer surface of the cylinder, and a gas diffusion layer is formed on the outside of the current collector layer by extrusion molding. A method for producing a cylindrical air electrode having a four-layered cylindrical shape by winding a membrane around the outermost periphery and then extracting a cylindrical jig. 6. The gas diffusion layer is formed by mixing carbon black and a fluororesin, adding water or an organic solvent containing a surfactant and kneading the mixture, and extruding the mixture using a circular slit into a cylindrical shape. The method for producing a cylindrical air electrode according to claim 5 .