The hybrid battery is under the rear seat. The Prime is also there, but extends under the cargo space. Never saw mention of the actual chemistry myself. It isn't LFP, as that isn't energy dense enough to fit in the tight spaces of a PHEV.
I think there is only one traction battery in a Prius Prime 2024. You seem to be implying there are two traction batteries?
No. Both only have one traction battery. The difference is in the size and which side of the sheet metal it's on. In the Prius HEV, the battery is on the inside of the car under the rear seat. The sheet metal floor goes under the battery. So to remove the battery, the cargo area and the rear seats are removed to gain access. In the Prime PHEV, the battery goes under the car. It's in roughly the same place, but the sheet metal floor goes over the battery, and the battery is encased in a weatherproof container. So to remove the battery, the car is placed on a lift and the battery is lowered like a transmission or rear differential.
As far the Prime's battery is concerned, you'll find all the relevant information in the sticky thread just above. The non-Prime also have Li-ion NMC type, not sure if using the same cells.
How would I gain access to the high voltage conductors from the traction battery -- to attach an Inverter?