I don't feel like I need a thin phone. I need a smartphone which can last for a week after a single charge. From what I understand, the energy density in modern battery processes is enough to pack 100 Wh battery into a phone, but for some reason we are stuck with 20 Wh for years.

You wouldn't want that weight. Well, 99.5% of smartphone users wouldn't want that weight. Maybe you would.

I believe the counterargument here is that we've gotten used to phones being relatively thin, and people have learned to charge their phones every night anyway. Something about stated vs. true desires, just like with the Minis where people said they wanted smaller phones but then nobody bought them. I believe it might be a similar thing where people say they want thicker phones with big batteries but they won't actually buy them when they realize they will be noticeably thicker and heavier.