Aluminium capacitors are a type of electrolytic capacitor. A capacitor is a two-terminal electrical component that can store energy, somewhat like a battery. Aluminium capacitors are polarised, meaning that the energy can only flow in a single direction. High purity grade Aluminium is used to create the anode foil and the cathode foil upon which electrolysis is applied to form an extremely thin insulating layer of aluminium oxide, which acts as the dielectric of the capacitor. Aluminium capacitors are found in many applications such as power supplies, computer motherboards and domestic appliances.
Dependent on the nature of the Electrolyte, capacitors may also be referred to as wet meaning they have a liquid electrolyte or solid. Solid Electrolytes may be hybridized with Aluminium but normally refers to Polymer or Tantalum based capacitors
Aluminium Electrolytic Capacitors
Electrolytic capacitors consist of an electrolyte which is a liquid or gel that consists of a large concentration of ions, and when voltage is applied across its terminals, it leads to charges being stored on the anode and cathode foils. The electric charge that can be stored by the capacitor is measured in Farads but usually in the range from nanofarads to millifarads. .Aluminium capacitors are used where high capacitance values to provide smoothing and filtering functions in the circuit. Commonly used in DC Power supplies due to their large capacitance and their compact size which helps to reduce the ripple voltage. Aluminium Electrolytic capacitors have reasonable Equivalent Series Resistance (ESR) but have the lowest leakage current from all capacitor types.
Polymer Electrolytic Capacitors
Polymer capacitors (also are known as polymer electrolytic capacitors or polymer e caps) have conductive polymer as their electrolyte material within a layered aluminium design. These capacitors combine unique properties from the polymer material in terms of high conductivity, extended temperature range and no risk of drying out – to make a capacitor that offers large capacitance and very low ESR (equivalent series resistance) with high ripple current capability and offer a longer operating life. Polymer capacitors offer a lot of package options between 2.2 to 470 microfarad
Hybrid capacitors (polymer hybrid aluminium capacitors) are a mix of wet electrolyte and solid polymer. In this sense, they combine the best of both electrolytes. These capacitors offer high endurance, low ESR, and a high tolerance for ripple current. Hybrid capacitors also feature stable electric characteristics at high frequencies whilst maintaining reliability. The liquid electrolyte keeps the Leakage current very low and also allows self-repairing of the aluminium foils which prevent a drop in capacitance.