A lot of cell makers moved to iron cobalt years ago because they're stable down to 3.2 a cell under load and don't have the negative effects (puff, over heat, pop etc) of magnesium cells have

It wasn't much more expensive and now the cell makers can put them in bigger packs like 10,000 mah and 12,000mah without going to 2p configurations. lighter and smaller form factor... thx to quad copters

Now HK has some of the best packs that are stable under 20 - 30c pulls, don't know why the other pack makers aren't moving to the more stable chemistry other than magnesium is 5,000 a ton and iron cobalt is 50,000 a ton or something close.