Fossil Fuels vs Batteries

No.12278443 ViewReplyOriginalReport
What did /sci/ Elon Musk think about his 2 Million Mile battery?

Why do people think that Lithium batteries can replace petro?
Gasoline has 12,888.9 watt-hour per kilogram
but Lithium batteries only have 243.06 watt-hour per kilogram?

I maybe missing something but why do people think batteries are competitive and will soon have battery powered passenger jets?