Calcium carbonate from chicken eggshells as filler in composite Nafion membrane for direct ethanol fuel cell: a molecular dynamics study

Abstract

AbstractBACKGROUNDDirect ethanol fuel cells (DEFC) need fillers to mitigate the issue of ethanol crossing over from the anode to the cathode, which lowers performance. Therefore, this study developed calcium carbonate (CaCO3) from chicken eggshells as a filler in a Nafion composite membrane for DEFC. Three cluster models of CaCO3 filler were developed, namely (CaCO3)2, (CaCO3)3, and (CaCO3)4, to form the Nafion composite membranes. The properties of composite membranes, such as proton conductivity, ethanol permeability, and selectivity, were studied using the molecular dynamics method. In addition, the three main factors influencing the composite membranes’ properties were analyzed in this study; these were cluster size of CaCO3, mass loading of the filler, and ethanol concentration.RESULTSThe results show that filler has reduced proton conductivity and ethanol permeability in the DEFC application compared to the Nafion membrane. However, the selectivity is used as a trade‐off between ion conductivity and ethanol permeability in the composite membrane, thus requiring a suitable size structure and mass loading to balance the high ion conductivity rate and reduce the ethanol permeability rate. The composite membrane C‐(CaCO3)4, which has a large cluster size in this study, shows that it is necessary to restrict ethanol permeability at a high ethanol concentration of 5 mol L−1. However, the structure size in cluster B – (CaCO3)3 – can reduce ethanol permeability but requires high mass loading by 5 wt%. Analysis of variance showed significant values for ion conductivity, ethanol permeability, and selectivity responses.CONCLUSIONCaCO3 successfully reduced ethanol crossover in DEFC, with all three composite membranes being suitable for use at low ethanol concentrations. However, specific size structure and mass loading are required to overcome ethanol crossover at high ethanol concentration. © 2023 Society of Chemical Industry (SCI).