This invention relates to improvements on an air cell, and more particularly to improvements on an air cathode.
The prior art cell comprises liquid electrolyte and an air cathode prepared by mixing powdered or granular active carbon particles with a water-repellent binder such as powder of Teflon and compressing the mixture into a thin sheet while being carried by a conductive holder such as a nickel net.
The conventional air cell of the above-mentioned type had the drawbacks that the electrolyte pervaded the air cathode due to capillarity during long storage or long period discharge at an extremely small current to thickly cover the surface of the active carbon particles used as one component of the air cathode, thereby prominently decreasing the surface area of the active carbon which could be contacted by air with a decline in the oxygen-reducing power, discharge area and consequently discharge voltage.
The concentration of the water-repellent binder has great effects on the discharge characteristics of the air cell. When the concentration is small, the discharge characteristics within the initial period are good. However, during storage, the electrolyte covers the surface of the cathode and long storage may not be possible. On the other hand, when the concentration is great, the working voltage becomes lower.