show increased restacking compared to the fct-EEM/fct-EEG composites (Figure ), while the fct-EEM and fct-EEG composites have a looser structure which is easier for the ions to get through the layers. As can be seen in Figure and Figure , the fct-EEM/fct-EEG membrane is wavy and has layered structures while the EEM/EEG composite membrane is more compact and flatter. This is because fct-EEG has more creases on the surface as a result of strain caused by intense functionalization. It is suggested that the wrinkled structures of fct-EEM/fct-EEG composites benefits the electrochemical performance of the composite electrodes by providing more edges and channels for the ions. The composite membranes had an average thickness of 2 µm, as measured by SEM. The mass ratios of fct-EEM/fct-EEG and EEM/EEG are both 1:3.