"Breakthrough" battery technology claims are the call of the new Dream Merchants looking to fleece investors.
Flying Car Dream Merchants were about three scams ago. Paul Moeller pulled this scam for 50 years! And still not one of his ever did more than hover, tethered to the ground.
https://en.wikipedia.org/wiki/Moller_M400_Skycar
There is a "flying car" already. It is called a
HELICOPTER.
The most modern helicopter is still incredibly difficult to learn to fly. Even a lightweight 2 seat helo with high efficiency piston engines and a lightweight airframe and long rotor blades, like the Robinson R22 is far less efficient than a fixed wing aircraft.
Unless and until some very primary, foundational laws of physics and aerodynamics are reinvented, and breakthroughs in materials science that are not even on the horizon are made, "flying cars" are nothing more than aspirational dreams that will deplete everyone involved of their money.