Differences between Three- and Two-Electrode Cell Supercapacitor Characterizations

3 Differences between Three- and Two-Electrode Cell Supercapacitor Characterizations 

One primary difference must be understood in characterizing supercapacitors using the three- and two-electrode cells. The information obtained using the former technique comes solely from the target electrode process without interference from the other electrode. With the latter technique, the information obtained is the sum of contributions from both electrodes. Interference from the second electrode must be subtracted to determine the sole contribution of the target electrode. The information obtained from the threecell technique is ex situ and does not necessarily reflect the real situation. However, it is commonly used for fast screening because it does not require an entire supercapacitor assembly The information obtained from the twocell method is considered in situ or close to the real operating conditions. 

For symmetric supercapacitor systems in which the two electrodes are identical, the information obtained using the two-electrode cell can be easily separated. For example, the obtained capacitance from the whole cell represents only half of the targeted electrode because the entire capacitance can be treated as two identical capacitances connected in series, as described in 

Chapters 1 and 2. However, for an asymmetric supercapacitor in which the two electrodes are not identical, it is not easy to separate the information from individual cells. In this case, the three-electrode cell may be used to distinguish the individual contributions from the two electrodes. 

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