Stability Analysis of Electrodeposition across a Structured Electrolyte with Immobilized Anions

Instabilities in electrodeposition that lead to formation of dendrites on metal surfaces place a significant limitation on important technologies such as batteries and microcircuits. In this paper, we show that a structured electrolyte with immobilized anions can improve the stability of electrodeposition as well as enhance the conductivity of the electrolyte at large overpotentials. A linear stability analysis of electrodeposition incorporating the effect of surface tension shows that the electrode surface is more stable at higher fractions of immobilized anions. Immobilizing even a small fraction (10%) of anions significantly improves stability compared to conventional liquid electrolytes. The analysis shows that the structured electrolyte stabilizes a wider range of perturbations than surface tension alone and reduces the growth rate of the most unstable perturbation. The stabilizing effects arise primarily at overpotentials large enough so that the metallic electrode is nearly depleted of ions in a liquid electrolyte. Under these conditions, the structured electrolyte maintains immobilized anions and mobile cations providing a stable current density at the metal electrode.