What happens with the batteries after their Lifetime?

I have no idea what happens then and how bad the batteries are for the environment. Please educate me!

Found something: https://www.youtube.com/watch?v=oKFOqMZmuA8 03:08min in the video if you don’t have time for the whole video. This video is really good and I highly suggest to watch it!

they just start to sag really badly… batteries actually dont have a say “lifespan”


They go to battery heaven where all the good little cells who didn’t vent go =’)