JPS6054164A - Zinc air battery - Google Patents

Abstract

PURPOSE:To absorb volume expansion caused by discharge reaction of negative active material and improve electrolyte leakage resistance by using porous metal as a negative current collector. CONSTITUTION:A film-shaped gas electrode 1 is formed by cylindrically winding a three layer film prepared by stacking together a current collecting layer, a catalyst layer, and a water repellent layer. A negative mix 6 prepared by kneading zinc powder, alkaline electrolyte, and gelling agent, and a negative current collector 7 connecting to a negative terminal plate 9 are accommodate in the gas electrode 1 with a separator 5 interposed. A brass foam rod is used as a negative current collector 13'. Carbon, nickel, copper, zinc, aluminium, brass, silver, gold, and platinum, and alloy of these metals, and metal plated plastic foam, fiber aggregate, and nonwoven fabrics can be used as electroconductive porous body for current collector.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a cylindrical air battery having a thin film gas electrode formed into a cylindrical shape, and more specifically relates to a cylindrical air battery having a thin film gas electrode formed into a cylindrical shape, and more specifically relates to a cylindrical air battery having a thin film gas electrode formed into a cylindrical shape.
This invention relates to an air battery that has excellent pain relief properties.

[Technical background of the invention and its problems]

A conventional cylindrical air battery has a structure as illustrated in FIG.

In the figure, l denotes a thin film gas electrode, which is constructed by winding a three-layer thin film in which a current collector layer, a catalyst layer, and a water-repellent layer are integrally laminated into a cylindrical shape. The upper end of the gas electrode 1 is welded to the periphery of a positive electrode terminal plate 8 via a lead wire 2, and the upper part of the gas positive electrode 1 is embedded in a gasket 3 to form a pot-shaped body. A negative electrode mixture 6 formed by kneading zinc powder, an alkaline electrolyte, and a gelling agent via a separator 5 and a negative electrode current collector 7 connected to the negative electrode terminal plate 9 are loaded inside the pot-like body. has been done. The opening of the kelp-like body is sealed with a gasket 4 made of synthetic resin such as polyethylene or polyglopylene. The peripheral portions of the positive terminal plate 8 and the negative terminal plate 9 are covered with insulating sleeves li, 12, and are clamped in a metal outer can 10 having an air intake hole 10'.

Here, the negative electrode current collector 7 is usually a round rod made of brass and having a diameter of 1 to 2 mm. In addition, the catalyst layer of the thin film gas electrode (1) uses conductive powder such as activated carbon powder, graphite powder, or powder of various metals as a base material, and the surface thereof is coated with oxygen such as platinum, palladium, silver, cobalt, etc. A porous molded body supported with a catalyst having reducing ability, bound with a water-repellent binder such as polytetrafluoroethylene (PTFE), and then formed into a plate or thin shape. , fine through-holes are uniformly distributed inside it.

In order to prevent the electrolyte from leaking from the porous 1↓ catalyst layer, for example, polytetrafluoroethylene, polytetrafluoroethylene-hexafluoropropylene copolymer, polyethylene-tetrafluoropropylene copolymer, etc. A predetermined amount of water-repellent substances (high contact angle with the electrolyte) such as ethylene copolymer and polypropylene are mixed in when bonding the catalyst-supporting substrate to form an integral water-repellent layer. ing.

Furthermore, in cases where leakage of electrolyte is not allowed, such as air electrodes used in air dry batteries or air electrodes of galvanic silicon sensors used to detect the concentration of dissolved oxygen gas in water, they are made from the above-mentioned materials. A water-repellent and oxygen gas-permeable thin film is attached to the air-side surface of the porous catalyst layer by an appropriate method such as heat fusion, pressure bonding, or adhesion to form an integral water-repellent layer. is being attempted.

When a battery with this structure is discharged, for example, if the negative electrode is of a type in which zinc powder is dispersed in an alkaline electrolyte containing a gelling agent, the discharge reaction at the negative electrode is an oxidation reaction of the metal. ``!, zinc reacts with nitrogen in the atmosphere outside the battery to form zinc oxide, 2Zn + 02 → '2ZnO, and the volume of the zinc 1y is 0.14c before discharge.
About 0.18 a! after discharge from rA/f/! /'! The amount of zinc alone increases by about 29 points. This volumetric expansion of zinc within the limited volume of the negative electrode active material presses the air electrode, which is the positive electrode, from the inside, and causes the sump liquid to flow out, forcing the 11L solution to the outside of the battery through the air electrode. , and more significantly, it causes the rupture of the cylindrical air electrode.

In order to prevent this, studies have been carried out such as making the air electrode thicker and increasing the amount of binder in the air electrode to increase water repellency and strong dust. It is still impossible to increase the resistance, significantly lower the discharge area, and prevent liquid leakage.

[Purpose of the invention]

The present invention is based on a discharge reaction of a negative electrode mixture. ``The purpose is to provide an air battery that absorbs expansion and has excellent electrolyte leakage resistance.

[Summary of the invention]

The air battery of the present invention is characterized in that a conductive space for absorbing the volume expansion of the negative electrode active material due to the battery discharge reaction is provided in the negative eve collection NET and body portion. The present invention will be explained below by taking a zinc-air battery as an example with reference to the drawings.

In order to provide this conductive space, the present invention uses porous bodies made of these metals instead of conventional brass round bar negative electrode current collectors, plate-shaped copper current collectors, and plate-shaped zinc current collectors. It is something to do. Figure 1 shows a conventional cylindrical zinc-air battery in which a brass round bar with a diameter of 2 mm is used as the negative electrode current collector (7).
The figure shows a conventional air B1R lead-acid battery in which the foamed brass of the present invention is used as the negative electrode current collector Q31 and the negative electrode current collector (7) and the non-negative terminal plate (9) are made of copper/stainless steel clad plate. A button-type zinc-air battery, Fig. 4 shows a zinc-air battery of the present invention with foamed steel as the negative electrode current collector side, and Fig. 5 shows a zinc plate with a zinc electrode (
Figure 6 shows a conventional prismatic zinc-air battery using foamed zinc as a negative electrode current collector (7) and a non-negative electrode current collector (6).
7) is a prismatic zinc-air battery of the present invention. Note that the same numbers as in FIG. 1 are used for FIGS. 2 to 6.

Each air cell is made of a water repellent layer, a 100 μm TFE porous film mixed with activated carbon powder containing platinum and rolled into a sheet by a conventional method as a catalyst layer, and a nickel wire mesh is collected. The electrification consists of an air electrode made by pressing these together, a separator made of polyamide nonwoven fabric, and a negative electrode mixture in which flying zinc powder is dispersed in an alkaline electrolyte containing a gelling agent.

The conductive porous body used in the present invention may constitute a negative electrode current collector by itself, or if the strength is insufficient, a separate current collector is provided, and this is The bodies may be connected by crimping or welding. Further, the conductive porous body itself may form a negative electrode active material.

The conductive porous material may include carbon, nickel, and fiil.
Metals such as , zinc, aluminum, aluminum, silver, gold, platinum, alloys, plated metals, 7fQ materials such as plastics, fiber aggregates, nonwoven fabrics, etc. can be used.

[Embodiments of the invention]

Thickness 100μ with uniform distribution of micropores with an average pore diameter of 10μ
Polytetrafluoroethylene film: water repellent layer; activated carbon powder with an average particle size of 100 μm carrying 5 parts by weight of platinum and polytetrafluoroethylene powder of 20% by weight of the activated carbon powder are used as a mixed powder, and this mixed powder is A film with a thickness of 0.5 mm prepared by rolling the film using a rolling method was prepared as a catalyst layer, and a 0.1 am l 40 mesh nickel wire mesh was prepared as an aggregate layer. These three islands are stacked in the above order and the total weight is 1 ton/Kpr? A thin J-shaped air electrode was made by pressurizing it at a pressure of .

The air electrode prepared in this way was made into a pure orange, and 60 to 150 pieces of zinc powder, which had been amalgamated with 3% water by weight, was hydroxylated.) A gelling agent was dispersed in the IJum solution. , using a zinc foil dispersed in the gel electrolyte prepared in 1 as a counter electrode, and a polyamide nonwoven fabric as a separator, LR6 type, L) 1.44 type, and zinc foam were used as current collectors by a conventional method. 100m x 1 for double negative electrode active material
Twenty square zinc-air batteries each having a size of 0 ports and 1 cTn were prepared. Table 1 shows negative electrode current collectors in this case, one using the conductive 19-porous material of the present invention and a conventional example not using the same.

These zinc-air batteries were discharged in air at 25°C at a discharge rate that completed discharging in 96 hours, and then stored in an atmosphere at 45°C and 90% relative humidity for 15 days. Observe the state of leakage. The percentage of leakage is also listed in Table 1, with the conventional battery as 100%.

Table 1 The above embodiments have been explained using a zinc-air battery as an example, but air, magnesium, and air iron batteries were used.

It goes without saying that air aluminum etc. can be applied to air 1; ponds.

Isao

[Brief explanation of the drawing]

Figures 1, 3, and 5 are sectional views showing conventional air batteries, and Figures 2, 4, and 6 are sectional views of cylindrical, button-shaped, and prismatic zinc-air batteries according to the present invention. show. 1... Gas electric camphor, 2... Lead wire, 3... Gasket, 4... Gasket, 5... Separator, 6...
Mixture, 7... Negative electrode current collector, 8... Positive electrode terminal plate, 9...
... Negative terminal plate, 10... Exterior can, 10'... Air intake hole, 11... Sleeve, 12... Sleeve,
13...Electroconductive porous body. Agent: Kensuke Chika, Patent Attorney (1 person) Figure 1 J 1f - Figure 3

Claims (1)

[Scope of Claims] l) An air electrode that electrochemically reduces oxygen (a nitrogen electrode), a negative electrode active material that emits electrons when electrically connected to the air electrode, and an air electrode that emits electrons when electrically connected to the air electrode. In an air battery composed of an electrolyte that connects the negative electrode active material through ion transmission, and a separator that prevents electrical contact between the air electrode and the negative electrode active material, the negative electrode active material and 4 Tl to the negative electrode current collector connected to the negative electrode terminal.
An air battery characterized by an i-type porous material. 2. An air battery according to claim 1, characterized in that the negative electrode current collector itself is made of a conductive porous material. 3) Percentage Permissible An air cell according to claim 1 or 2, characterized in that the negative electrode active material itself is a conductive porous material.