The big fly in the ointment is the energy density of what ever is used as a power source. Petrol (gasoline) has 53 times the watt/hour capacity of a lithium ion battery.
Actually energy density is volumetric. With aircraft we're more concerned with weight. Which is termed specific energy. Yes, the figure is close to 50x, but your next statement is not correct:
In other words for every kilo of petrol you need 53 kilograms of lithium ion battery.
If that were true the Telsa Model S would need a couple of tons of battery. It doesn't have anything like that.
You're forgetting that internal combustion engines at best convert 20% of their fuel energy to power. Whereas an electric drive can achieve over 90%.
This brings the specific energy problem down close to a factor of 10 rather than 50.
It's still a big hurdle to overcome, yes. But there are other battery technologies in the wings that may help close the gap.