Putting that much power density on your lap is kinda scary. It's like carrying a slab of C4. Imagine if the galaxy note incident happen again but with a much much higher power density battery which can go kaboom.

How would a C14 slab would go kaboom? Its only role is to give radiation which is transformed into heat or electricity.

I don't expect any explosive parts here.

I was talking about a high capacity battery that can power a laptop for a week, not the nuclear battery from the article.

Doubt it. Look at the evolution of mobile phones: they went from staying alive for a week to needing a charge overnight. People gripe around the margins, but in general seem OK with that.

It would be a major thing for car batteries - lighter batteries with longer charge means you get more range from two factors - less stuff to move and more capacity to do it.