Water is notoriously difficult to get rid of, even after rigorous drying of all cell components, and is always present albeit at very minor concentrations. Later the observed C2H4 is formed likely together with the largely insoluble (CH2OCO2Na)2 (NEDC) as a result of EC reduction (Eq. 4) . These gases are just observed to occur simultaneously since the cell is being cycled galvanostatically.