It's also hard because batteries don't get lighter as they deplete, so you're landing a plane with the exact same weight as what you took off with, meaning you need much more rugged (and heavy) landing gear. This is extremely significant when you consider that a fully loaded 747-8 is 970,000 lb, of which up to 326,000 lb is fuel (per Wikipedia's numbers).
It's a hard problem, and most proposed solutions are extremely novel and risky, like having an all-battery tugboat that tows the plane up to cruising speed/altitude before returning to the airport to charge or get a battery swap— obviously bad because risky, also adds 50% to runway capacity to land all the tow planes.
It's a hard problem, and most proposed solutions are extremely novel and risky, like having an all-battery tugboat that tows the plane up to cruising speed/altitude before returning to the airport to charge or get a battery swap— obviously bad because risky, also adds 50% to runway capacity to land all the tow planes.