The story is about how to spend grant money when you can get it for free...
For the same reason that EVs are impractical for 99% of the world, battery powered or assisted airplanes are also impractical. Even when the aircraft is sitting on the ground and the batteries are being charged, electricity isn't free. The batteries aren't free. The maintenance isn't free. The disposal of toxic dead batteries isn't free. The problems with high tech batteries in EVs as well as commercial aircraft for auxiliary power have been documented.
The sad reality is that even with newer battery designs, they make no sense at all for aircraft as far as powering the aircraft in flight. Naturally of course if you can get some grant to research what we already know, you'll find a means to spend it and make it look like a techno breakthrough.