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Comment by JoeAltmaier | Hacker News Reader

I don't get it. It contains its own oxygen in an electrolyte matrix. So it isn't any lighter than existing lithium batteries? What's the point?

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Did we not read the same article?

Lithium Air batteries could offer up to 4x the energy density, this one is 2x.

Part of the reason this hasn't been done before is that previously the oxygen introduced to the battery was from the air and other components of air damaged and degraded the battery rapidly.

This battery is sealed with all the Oxygen it needs as a LiO mixture stored in a cobalt matrix to stabilize it. Thus is doesn't degrade.

>...prototype stores twice as much juice as the lithium-ion cells the Gigafactory will turn out, and which could eventually do better than that.

Twice as much on a per-volume basis? Or per-weight?

Energy density is measured in J/L, so volume.

Specific energy is measured all sorts of ways. J/L is not very helpful for cars at all. So this battery will probably not be very interesting for transportation?

Just because the energy density is measured in a certain way, it doesn't then follow that the energy density when measured in a certain way is going to be significantly worse.

J/L is actually one of the more important ways to measure battery efficiency for transportation. In many discussions around this theme you'll find this to be used in comparison with a gas tank for size and that ultimately translates into range, arguably the most important feature of an electric car.

Higher energy density means higher range, all other things being equal, and with the weight of cars being what they already are a battery weighing a few hundred pounds would be perfectly acceptable.

So J/L is actually very helpful.

Per-weight is almost double current lithium batteries. But the much bigger issue it solves seems to be the energy loss versus other types of lithium-air batteries which can lose up to 30% to heat, versus 8% in the lithium-oxygen battery.

The MIT press release has more details, but the cathodes are half the weight of the current Lithium batteries and so can store almost double the energy for a given weight.

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