Asymmetric systems battery electrode

Asymmetric Systems Using a Metal Oxide Battery-Like Electrode in... 

The first asymmetric systems presented in the literature used a rechargeable battery-type electrode combined with an activated carbon capacitive electrode, either in aqueous [99,100] or in organic [101-109] electrolytes. The reason which led to follow this direction is the possibility to enhance at the same time the cell voltage and the cell capacitance [110-112],... 

As it was already described in Section 8.2.1, the total capacitance of a supercapacitor is given by Equation 8.1. In a symmetric capacitor with equal values of capacitance for the positive (Cj) and negative (f2) electrodes, the total capacitance of the system is half the capacitance of one electrode. In the asymmetric device, as the capacitance of the battery electrode is much higher than the capacitive one, the capacitance of the system approaches that of the electrode with the smallest value. In other words, the capacitance of the asymmetric configuration combining a battery-like electrode with a capacitive one will be close to the value of the capacitive electrode, i.e., twice larger than that for a symmetric configuration with two capacitive electrodes. 

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