That is true, but they also have several orders of magnitude higher power density. Maybe the battery technology to make this work just doesn't exist -- I'm ima

That is true, but they also have several orders of magnitude higher power density. Maybe the battery technology to make this work just doesn't exist -- I'm imagining something that can absorb enough energy in, say, ten seconds or less, to make it around the track a couple times. Lithium ion can store huge amounts of energy, but charge times are slow. Capacitors can charge very quickly, but have very little capacity. I don't know if there's some technology that splits the difference. Lithium Titanate? Solid state batteries?