In this Update, Aptera explains how its proprietary battery packs will be built, first in Korea and then in California. Interesting to note that the larger battery packs - the 60kWh and 100kWh - won't use more batteries than the 25kWh and 40kWh packs: They will use taller, higher-capacity cells so their modules will fit within the common pack architecture.
I wonder how much lighter a quarter of the high-capacity 100kWh battery is than the low-capacity 25kWh battery? I'm imagining a lightweight Aptera Sport 25.