Electrolytic Capacitors


What is the differences between dielectric capacitors and electrolytic capacitors? Why does a electrolytic capacitor store more charges under same voltage than dielectric capacitors?


All capacitors involve a dielectric. Some are made up from a pair of solid conductors separated by a very thin film of solid dielectric material. Electrolytics was a "breakthrough" in capacitor technology in the early 1900's. Instead of placing a solid wedge of something (which can be quite thin), an electrolyte solution is used. The electrolyte serves as the 2nd electrode. The electrolyte is not the dielectric. The dielectric is a very thin layer of oxide which is grown electro-chemically in production. The thickness of this oxide layer is on the order of .01um, much smaller than any piece of plastic or ceramic that could be used as a separator. To contact the electrolyte, another piece of foil is used, but it is the electrolyte that is truly the plate.

The amount of charge a capacitor can hold at a certain potential (its capacitance) depends on the ratio of surface area to distance between the electrodes. In electrolytic capacators the distance between electrodes is so small that the capacitance can be quite high. With electrolytic capacitors care must be taken that the voltage is never reversed in polarity. That destroys the oxide layer.

This information is brought to you by M. Casco Associates, a company dedicated to helping humankind reach the stars through understanding how the universe works. My name is James D. Jones. If I can be of more help, please let me know.