It's also much heavier and much more expensive. This really isn't a breakthrough more than it is a special case optimization. Any new design could easily have accommodated a similar capacity battery with traditional construction just by making the car 2cm taller or whatever.

I mean, lithium batteries are already pretty space-efficient. This kind of optimization surely has a home in some application (to be clear: it already does in consumer electronics!). I'm just not sure cars are where it's best applied.