Operation of Direct Methanol Fuel Cells

High molecular weight PVA-modified PVA/PAMPS proton-conducting membranes with increased stability and their application in DMFCs

“…Direct methanol fuel cells (DMFCs), employing liquid methanol as a fuel, offer an attractive option for portable devices due to their simplicity in terms of system structure (easy storage and supply), and because there is no need for fuel reforming or humidification [1]. For obtaining higher power density, membranes showing high proton conductivity coupled with low methanol permeability are highly desirable [2]. In DMFCs, methanol crossover (passage from the anode to the cathode of the cell) not only causes loss of fuel but also reduces performance at the cathode due to the mixed reaction of methanol oxidation with oxygen reduction [2].…”

“…For obtaining higher power density, membranes showing high proton conductivity coupled with low methanol permeability are highly desirable [2]. In DMFCs, methanol crossover (passage from the anode to the cathode of the cell) not only causes loss of fuel but also reduces performance at the cathode due to the mixed reaction of methanol oxidation with oxygen reduction [2]. Although much effort has been undertaken to overcome the above problem [3][4][5], the issue of membrane stability, particularly hydrolytic and chemical stability, is still a big barrier and is recognized as a key factor that affects fuel cell performance [3,6].…”

Methanol adsorbates on the DMFC cathode and their effect on the cell performance

“…This severe crossover problem occurred even after using the modified membrane, from which one can realize how serious the methanol crossover problem is in the case of using unmodified Nafion type membranes. Recently, Qi et al [19] reported that the DMFC performance was declined (over 20%) at 72°C , after cathode of the cell was being diffused with 1 M methanol solution during the overnight idle period; they concluded that the flooding of methanol solution on the cathode side was responsible for the decline in the performance of the cell. In the above condition, we suspect that there would also exist a possibility of the formation of methanol intermediates on Pt sites of the cathode, which is in the atmosphere of flooded methanol solution and may also lead to the decline in the performance.…”