Properties

Properties

From an electrical point of view the supercapacitor is a very complex system. It is built with materials developed for the use in the battery domain and it has nevertheless capacitor like properties. The aluminum collector provides only the electronic conduction contribution to the charge transport. The separator allows only the electrolyte ionic conduction between the two electrodes. In the carbon electrode both the electronic conduction inside the carbon particle and the ionic conduction in the electrolyte around the carbon particles contribute to the electrical charge transport. The supercapacitor characterization is very sensitive to the measurement method which is used. The IEC standard organization has issued the IEC62391 series of directives [1,2,3] to establish a base for the testing conditions.

The capacitor conditioning before the measurement is also an important parameter which may lead to great divergences in the results. The supercapacitors need hours before to reach an equilibrium state because some areas are very far or are very difficult of access for the ions. It does mean for example that after a long polarization time, the capacitance and the ESR values will be different of those found in the absence of a previous polarization. Moreover this measurement effect will be mixed with the capacitance fading due to the aging. Consequently, it is capital to always precisely define the experimental conditions of the measurements.

[1] IEC 62391-1. Fixed electric double layer capacitors for use in electronic equipment - Part 1: Generic Specification, Ed. 1. 2006.

[2] IEC 62391-2. Fixed electric double layer capacitors for use in electronic equipment - Part 2: Sectional specification - Electric double layer capacitors for power application, Ed. 1. 2006.

[3] IEC 62391-2-1. Fixed electric double layer capacitors for use in electronic equipment - Part 2-1: Blank detail specification - Electric double layer capacitors for power application Assessment level EZ, Ed. 1. 2006.

Source: Garmanage: Roland Gallay