Patent ID: 7227737

Claim:
A double-layer capacitor, comprising: an electrolyte; a positive electrode layer of a first thickness, the positive electrode layer being immersed in the electrolyte; and a negative electrode layer of a second thickness, the negative electrode layer being immersed in the electrolyte; wherein: a first sub-capacitor is formed at an interface between the positive electrode layer and the electrolyte; a second sub-capacitor is formed at an interface between the negative electrode layer and the electrolyte; and the first and second thicknesses are selected by: determining a positive voltage limit for the first sub-capacitor and a negative voltage limit for the second sub-capacitor; dividing the positive voltage limit by the negative voltage limit to obtain a first ratio of the second sub-capacitor to the first sub-capacitor; and setting relative thicknesses of the positive electrode layer and the negative electrode layer so that capacitance of the second sub-capacitor is substantially equal to a product of the first ratio and the capacitance of the first sub-capacitor.