A Novel Approach to Designing Highly Efficient and Commercially Viable Biofuel Cells

A biofuel cell is an electrochemical device in which the energy stored in a fuel, such as ethanol, is converted to electrical energy by the means of the catalytic activity of enzymes. Biofuel cells have traditionally suffered from low power densities and short lifetimes due to the fragility of the enzyme catalyst. Utilizing a novel quaternary ammonium salt treated Nafion membrane for enzyme immobilization in a biofuel cell results in increases in power densities and enzyme lifetimes to commercially viable levels. Additionally, this method provides sufficient protection to develop a membrane electrode assembly style (MEA) biofuel cell, an important step for commercialization. Previously, it has not been possible to create a MEA-style biofuel cell due to the denaturing of the enzyme that would occur at the high temperatures experienced during the heat pressing step of fabrication. Quaternary ammonium salt treated Nafion membranes provide sufficient protection for the enzyme to retain activity after exposure to temperatures of 140°C. Thus, a MEA-style biofuel cell can be created. Preliminary results yield biofuel cell MEAs with power densities ranging from 0.15 to 1.49 mW/cm2 and open circuit potentials of 0.360 to 0.599 V.