For my wild life camera, I want a small cell that can provide 0.5W for 8 hours or more. It doesn't seems rechargeable lithium ion batteries have that energy density. I don't mind if the cell is non-rechargeable, so I've considered the lithium coin cells and zinc-air batteries.
But it seems the internal resistance on those are terrible:
For a CR2477, I estimate the resistance at 910 ohms! Energy density = 2.96 MJ/L
For a 675 hearing aid cell, I estimate 34.7 ohms. Energy density = 6 MJ/L !
So if I use those, there's no way I can draw 0.5W, if at all, without having all the energy consumed by IR? (is IR the only factor causing lower capacity?)
Is this a fundamental limitation to those battery chemistries or can someone point me to cells that allow higher current draw?
According to Wikipedia's energy density page, it claims there are non-rechargeable lithium batteries with an energy density of 4.32 MJ/L. That would be awesome, but where do I find them? (I'm only seeing 2.96 MJ/L for a CR2477 coin cell).
Tadiran Batteries have LiSOCl with an integrated super capacitors. Those are not rechargeable and are quite expansive compared to the more common CR types. The standard LiSOCl AA cell can manage 100mA/100mSec pulse at ~3V (Dropping from 3.6V). There are many manufacturers of such batteries (Tadiran, Saft, Xeno, EEMB and others). Of course, there are also D sized cells with 19Ah capacity and much higher pulse capabilities.