31-05-2012, 12:37 PM
Simple Capacitors to Supercapacitors
SUPER CAPACITORS.pdf (Size: 879.69 KB / Downloads: 325)
INTRODUCTION
This paper offers a concise review on the renaissance of a conventional capacitor to
electrochemical double layer capacitor or super capacitor. Capacitors are fundamental electrical circuit
elements that store electrical energy in the order of microfarads and assist in filtering. Capacitors have
two main applications; one of which is a function to charge or discharge electricity. This function is
applied to smoothing circuits of power supplies, backup circuits of microcomputers, and timer circuits
that make use of the periods to charge or discharge electricity. The other is a function to block the flow
of DC. This function is applied to filters that extract or eliminate particular frequencies. This is
indispensable to circuits where excellent frequency characteristics are required.
EXPERIMENTAL PART
The invention of Leiden jar in 1745 started the capacitor technology; since then, there has been
tremendous progress in this field. In the beginning, capacitors are used primarily in electrical and
electronic products, but today they are used in fields ranging from industrial application to
automobiles, aircraft and space, medicine, computers, games and power supply circuits. Capacitors are
made from two metallic electrodes (mainly Si) placed in mutual opposition with an insulating material
(dielectric) between the electrodes for accumulating an electrical charge. The basic equation relating to
the capacitors is:
ELECTROLYTIC CAPACITORS
The next generation capacitors are the electrolytic capacitors; they are of Ta, Al and ceramic
electrolytic capacitors. Electrolytic capacitors use an electrolyte as conductor between the dielectrics
and an electrode. A typical aluminum electrolytic capacitor includes an anode foil and a cathode foil
processed by surface enlargement and or formation treatments. Usually, the dielectric film is fabricated
by anodizing high purity Al foil for high voltage applications in boric acid solutions. The thickness of
the dielectric film is related to the working voltage of the aluminum electrolytic capacitor.