My friend asked me about the battery and here are some things I couldn't answer!

1) Does anyone know if the Prius battery's capacity decreases because of use?

Now, I know this situation would be a long time from now but...
2) If the Prius' battery needed to be replaced, what would happen to the dead Prius battery? Where would it go? (Landfills?)

the best answer i could give him would be... you wouldn't need to replace the whole battery and probably just individual sections of it. that way it wouldn't harm the environment as much.. but I dunno

A Prius a day keeps the doctor away!