The energy density of gasoline is around 46 megaJoule per kilo according to this reference.
Energy density - Wikipedia, the free encyclopedia For Lithium ion batteries energy density is around 0.8 megaJoule per kilo. That implies, in a perfect world a range of (at best) 2% of what can be achieved from kerosene.
That's ignoring all the other show stopping objections, like could they ever be made acceptably safe, and the fact that no weight would be lost in travelling so aircraft would have to land at maximum take off weight with all that implies. Also the cost of the batteries would be vast, and there isn't enough lithium for such applications anyway.
If you are going to think the unthinkable, it might be better to ask what would we have to do if we were no longer able to fly at all, at any cost? By all means ask that question but as this is an aviation forum you might do better raising it elsewhere.
