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The link in the YC headline is to a press release. However, the press release links to the actual paper, which provides a wealth of tehcnical detail. This is

The link in the YC headline is to a press release. However, the press release links to the actual paper, which provides a wealth of tehcnical detail. This is a rechargeable zinc air battery. Not a primary battery. Although, this is early stage battery research. There is nothing about cycle life or Wh/kg. IMHO, this is years, potentially decades, from commercialization. Still quite interesting.

fuzzfactor 3y ago
Nothing about current capacity either. Each 2 kilos of elemental zinc that can be oxidized to release electricity requires 1 kilo of oxygen to be brought into the reaction. So it's efficient in some ways since you don't have to supply the oxidant as part of the battery package. But it takes a lot of cubic feet of oxygen to make a kilo, it's not easy to get that many grams of oxygen into the eletcrolyte very fast, and air is only about 21 percent oxygen. So it takes way more kilos of air than it does zinc. Rechargeable or not, for very high current duty you may just need pure oxygen and it may be better under pressure, or perhaps compressed air might up the current capacity in a worthwhile way. Interestingly, in some industrial oxygen measuring devices the sensor itself is a zinc-air "battery" consisting of a thin film of teflon (which is somewhat porous to oxygen) streched across the only exposed face of an electrolyte-moistened metallic zinc electrode, surrounded by a reserve of gel electrolyte that replenishes as it creeps into the layer between the zinc and the teflon film. At nominal 21 percent ambient oxygen content a steady current is produced from the rate of oxygen diffusing through the film making contact with the zinc, measured by a meter, and calibrated to display 21. In reduced oxygen atmospheres the minuscule oxygen directly in contact with the zinc is rapidly depleted and the meter declines accordingly into the "unsafe" region.
- distract8901 3y ago
  Conversely, zinc air primary cells are also used as pressure actuators. Don't have a link handy, but Big Clive on YouTube did a series of videos a while back on some industrial air fresheners and grease dispensers that use one of these cells to very slowly create a large amount of air pressure to squeeze out viscous liquid over time. The amount of gas released can be controlled with the current through the cell. Very interesting technology!
- bombela 3y ago
  oxygen density: 1.429 g/L oxygen un air: 21% 1kg/1.429g/L~=700L of oxygen/21%~=3.332m³ of air (~=118 cubic feet)

fuzzfactor 3y ago

Nothing about current capacity either. Each 2 kilos of elemental zinc that can be oxidized to release electricity requires 1 kilo of oxygen to be brought into the reaction. So it's efficient in some ways since you don't have to supply the oxidant as part of the battery package. But it takes a lot of cubic feet of oxygen to make a kilo, it's not easy to get that many grams of oxygen into the eletcrolyte very fast, and air is only about 21 percent oxygen. So it takes way more kilos of air than it does zinc. Rechargeable or not, for very high current duty you may just need pure oxygen and it may be better under pressure, or perhaps compressed air might up the current capacity in a worthwhile way. Interestingly, in some industrial oxygen measuring devices the sensor itself is a zinc-air "battery" consisting of a thin film of teflon (which is somewhat porous to oxygen) streched across the only exposed face of an electrolyte-moistened metallic zinc electrode, surrounded by a reserve of gel electrolyte that replenishes as it creeps into the layer between the zinc and the teflon film. At nominal 21 percent ambient oxygen content a steady current is produced from the rate of oxygen diffusing through the film making contact with the zinc, measured by a meter, and calibrated to display 21. In reduced oxygen atmospheres the minuscule oxygen directly in contact with the zinc is rapidly depleted and the meter declines accordingly into the "unsafe" region.

distract8901 3y ago
Conversely, zinc air primary cells are also used as pressure actuators. Don't have a link handy, but Big Clive on YouTube did a series of videos a while back on some industrial air fresheners and grease dispensers that use one of these cells to very slowly create a large amount of air pressure to squeeze out viscous liquid over time. The amount of gas released can be controlled with the current through the cell. Very interesting technology!
bombela 3y ago
oxygen density: 1.429 g/L oxygen un air: 21% 1kg/1.429g/L~=700L of oxygen/21%~=3.332m³ of air (~=118 cubic feet)