I'm wondering whether I'd prefer to not be stuck underwater with a huge pack of lithium cells, or to not be stuck underwater with a tankful of liquid oxygen and another tank full of diesel?
I'm attracted to the idea of battery submarines mostly because you'd be latching onto a huge (and growing) commercial development world. Much less need for highly specialized tech.
Thinking it through, assuming that propulsion is the gating factor for submarine adoption (maybe it isn't), what happens when pretty much any nation can afford a silent undersea navy?
The next thing I'll hear about is recharging station surface ships.
https://www.thedrive.com/the-war-zone/41075/canadian-submari...
Full size submarines can recharge their own batteries on the surface using diesel engines. Only some small, short-range submarines rely on other vessels for recharging.