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LiFePo4 still discharges when sub zero. The danger is if you try to recharge them while they are still at sub-zero temps.
Of course performance will not be as good at sub zero as at room temp.
There are a lot of competing battery chemistries out there and any given complaint will not apply to all those chemistries (like the cobalt argument as Co is not used in the chemistry I listed above).

carry on