Simulation Studies on the Design and Analysis of Interdigital and Fractal-Based Micro-Supercapacitors

Micro supercapacitors (MSC) are recently replacing traditional batteries in flexible and portable electronic devices owing to their outstanding features such as high power density and long cycle life. In-plane supercapacitors are usually built in an interdigital electrode (IDE) structure because of its fabrication simplicity and flexibility. This helps to reduce ion diffusion length and enables easy on-chip integration of the device. Recent researches show that by replacing the interdigital electrode structure with the new architecture technique of Fractal electrode design, the effective area of the electrode-electrolyte interface and capacitance can be increased. This work investigates the effect of the device architecture on the energy storage capacity of in-plane MSCs. IDE and Fractal-based electrodes are simulated using COMSOL Multiphysics and analyzed for performance using cyclic voltammetry, galvanic charge-discharge technique and electric field distribution. The results indicate that the device with fractal design has more areal capacitance than the traditional interdigital structure. The highest capacitance was achieved by the proposed Sierpinski Fractal electrode design which exhibited 85.59% more areal capacitance than the conventional IDE. This can be attributed to the significant increase in effective electrode area and the edging effect of the electric field in the sharp edges of fractal electrodes.