Improved performance of sulfonated polyimide composite membranes with rice husk ash as a bio-filler for application in direct methanol fuel cells

Abstract

The main problem with using membranes in a direct methanol fuel cell is the proton conductivity and methanol permeability that reduces the performance of the membrane. In addition, the cost of the membrane is very high and remains the main issue for the commercialization of Direct Methanol Fuel Cell (DMFC). To solve this problem, this study introduces rice husk ash (RHA) as a bio-filler in sulfonated polyimide (SPI) composite membranes. The bio-filler is expected to reduce the cost of the membrane and at the same time increase the performance of the membrane. In this work, agricultural rice husk waste was subjected to oxidation to produce RHA. The composite membrane displayed maximum values for the ion exchange capacity (0.2829 mmol g−1) and water uptake (55.24%). It was observed that the proton conductivity (0.2058 S cm−1) was higher than that in the pristine SPI membrane. The methanol permeability of the SPI-RHA membranes was reduced to 24 times lower than that of the pristine SPI membrane. In the DMFC passive single-cell test, the maximum power density was increased from 8.0 mW cm−1 to 13.0 mW cm−1 using a composite membrane with 15 wt % RHA. These composite membranes have proven that the addition of RHA enhanced the performances of the fuel cell and have a very high potential to act as an alternative bio-filler for the membranes used in a direct methanol fuel cell.