er...you all make me more confused, last day, I have read an article
about supercapacitor, the instant discharge of the capacitor is stronger than that of the battery, but the energy density of the battery is far less than that of the li-battery.
That still make sense. One is a marathon runner (battery), the other is a sprinter (capacitor). Just because a sprinter can run faster doesn't mean they can run for longer than a marathon runner, even if they ran at a slower speed.
A capacitor is a small tank with a very large opening you can pour electrons out of faster, but the total available is less. A battery is a much larger tank but has a smaller opening so you have more total electrons you can pour out, but you the speed at which you can pour them out is slower.
Or it's like a bank account with a $10k daily withdrawl limit but only has $100k in it versus a bank account that has a $1k daily withdrawl limit but has a billion dollars in it.
Nitromethane and gasoline are the same. Nitromethane produces less energy per mass burnt but, for a given combustion chamber volume, you can burn so much more of it in a single combustion cycle that you can make up for the lower energy per mass burnt in order to produce higher power than gas. So high power, low run time.
Gasoline produces more energy per mass burnt but chemistry prevents you from burning too much at once, so lower power but much much longer runtime. That's why many small model airplanes use nitro engines. More power with a smaller, lighter engine. More acrobatic. Gasoline engine planes of the same size have less power, but run for much, much longer on the same amount of fuel.