Is that possible?

And I have a question... when I charge a capacitor... Is possible to use that energy that the capacitor has by using it little by little, or when you discharge a capacitor, the capacitor discharges in the same moment that you use the energy?

batteries are composed of electrochemical cells. a capacitor is not an electrochemical cell.

 

yes, it is possible to use a capacitors charge over a long period of time.

If you short circuit a capacitor (attach a single, short wire across the terminals) then it will discharge very very quickly, because the wire has a low resistance, and so there's a big current going through it. Remember a capacitor stores charge, and current is the flow of charge, so if you have a big current then there's lots of charge leaving the capacitor per second.

 

However you can slow this down by putting more resistance. If you attach a resistor and LED to a small/average sized capacitor then it can keep the LED lit up for 10 or 20 seconds.

 

I have a special "supercapacitor" in front of me that is 20F (a massive capacitance) and this could power a mini robot for several minutes, and can keep an LED lit for many minutes (I've never tested how long, but if Q=CV, I charge it up with 2.5V, so Q=50C. Then Q=It, a 100ohm resistor/LED at 2.5V will draw 2.5/100 amps, giving a time of 2000seconds, or over 30mins, wow, that's more than I expected!)

 

Just for interest: sometimes you do want a quick discharge though. If you need a very high current, higher than you get from the mains or a generator, then an easy way to do this is store lots of charge (energy) in a capacitor, and then discharge it all at once, giving you one mega big current!