Polymer separator and low fuel concentration to minimize crossover in microfluidic direct methanol fuel cells

Microfluidic direct methanol fuel cell (DMFC) has some key issues, such as fuel crossover and water management, which typically hamper the development of conventional polymer electrolyte-based fuel cells. Here a method of minimizing fuel crossover in microfluidic DMFC is reported. A polymer separator at the interface of the fuel and electrolyte streams in a single-channel microfluidic DMFC is used to reduce the cross-sectional area across where methanol can diffuse. Based on the optimized fuel rate, fuel concentration and pore radius, a maximum power density of 7.4 mW cm−2 was obtained with the separator using 2 M methanol. This simple design improvement reduces the voltage loss at the cathode and leads to better performance.