That's good, but is that what's used in "used car-batteries with degraded capacity"?
Used car batteries are conventional unsealed, lead-acid batteries. Lithium-iron-phosphate (aka LiFePO4, LFP) batteries is a different battery chemistry altogether. It is touted as the answer to a deep-cycle, lithium-based electrical storage that the traditional lead acid batteries occupy.
I think they mean used EV batteries - EV batteries that are at the end of their useful life in cars.
That makes more sense.
Also way better cycle life, but the density is slightly lower.