[Robotbeat]

They're using an existing certified battery for the prototype, not for operations. It takes time to certify battery chemistries.

And small general aviation aircraft like these usually only have a small portion of their takeoff weight as fuel, maybe 20-25%. But passenger aircraft may have 50% of their takeoff weight be fuel (for instance, 777 on long haul flights). Electric aircraft like Eviation will need to go further (55%). This is something you can do with a cleansheet design like Alice, but can't with a mere conversion designed literally over 70 years with manufacturing and materials from 70 years ago.

And you can apply the same principle of increasing take-off weight fraction for kerosene-powered aircraft as well. The Virgin GlobalFlyer was 82% fuel on takeoff. It flew around the world and then some. Kerosene is much better than it needs to be to enable modern flight.

You're absolutely right about Alice being late, but the design concept is a good example of what is possible. You combine state of the art but existing lithium ion chemistry (which needs some work for aviation certification but IS used on the ground already) with state of the art lift to drag ratio (and perhaps additional innovations, like wingtip propulsion to reduce losses from wingtip vortices) with efficient enough structural mass to enable 55% of the takeoff weight (as well as landing weight, of course) to be battery.

These things multiply together to enable long range.