Proton-exchange polymer composite membrane of Nafion and microcrystalline cellulose for performance improvement of direct glycerol fuel cell

In this research, glycerol was used as fuel for a direct glycerol fuel cell (DGFC). Nafion (NF) was used to fabricate a proton exchange membrane and microcrystalline cellulose (MCC) was used as a filler for fabricating the NF composite membranes with different MCC loadings (0, 5, 10, or 15 wt%). The composite membranes were characterized using X-ray diffraction XRD for study of the crystallinity index (CI), SEM-EDS was applied to observe the atom dispersion of membranes, and FTIR-ATR was used to identify the chemical bonds of samples. The results showed that the 15 % MCC/NF membrane had a greater CI than the 5 % MCC/NF composite membrane, while the atom dispersion of the 5 % MCC/NF membrane was better than the others. The composite membrane properties were tested based on water uptake, solubility, ion exchange capacity, chemical degradation, 1 M and 2 M glycerol permeability, proton conductivity, selectivity, and fuel cell performance. The 5 wt% MCC loading increased the water uptake and proton conductivity and decreased the glycerol crossover compared to the other membranes. However, 15 wt% MCC had more durable chemical membrane degradation than the 5 wt% MCC membrane and the solubility test identified that the 5 %, 10 %, and 15 % MCC/NF composite membranes had 2.97, 3.08, and 4.92 times, respectively, that of the recast NF membrane. The highest selectivity (1.54 × 105 Sscm−1) of the membranes was recorded for the 5 % MCC/NF composite membrane at 50 °C. The DGFC performance with 1 M glycerol at 70 °C of the 5 % MCC/NF composite membrane had a maximum power density 18.07 mW/cm2 and a current density 0.139 mA/cm2.