45b5192f_apacitor_Engineering_Reference__Type_of_capacitor
[Characteristic] Oxide film formed by aluminum electrode surface is used as dielectric. The paper impregnated with the electrolytic solution is used to let the electrode facing without any gap glue on oxide film surface. It is necessary to note when using as there is polarity in the terminal. Although it is high capacity, there are many inductance components and the frequency characteristic is inferior, and is mainly used for smoothing the electric power supply. [Type of capacitor] 
Aluminium electrolytic capacitor
Types of capacitor｜Engineering Reference
Type of capacitor