UC San Diego

An electrochemical cell is an energy storage device that involves both electrons and ions as part of the storage mechanism. In this work, we investigate the use of nanostructures on the electrodes of the cell to increase the active surface area, and the consequent quantum effects introduced to the cell. With regards to capacitive storage, we predict quantum capacitance will affect the storage capacity of electrons on the electrode, and limit the increase in total capacitance of the device from scaling with the increase in active surface area. Furthermore, we predict geometric effects will affect the screening ability of ions in the electrolyte, allowing device current during charge/discharge cycles to be higher than for a flat electrode. With regards to battery-like storage, we predict the density of states of the electrode will affect the device current, possibly increasing device currents for higher overpotentials compared to a flat electrode battery. This last prediction is based on treatment of the redox reaction process as a tunneling process between electron and ion, akin to a recombination process between electron and hole in a solid state device such as a reverse biased diode.