Investigation of passive direct methanol fuel cell (DMFC) at the open circuit condition

In this work, a transparent passive DMFC was constructed to investigate the transients in open circuit voltage (OCV) and the cell temperature difference, which changed as a consequence of the methanol crossover phenomenon, including anode temperature difference (ATD), cathode temperature difference (CTD) and methanol solution temperature difference (MTD). Experiments were carried out in a passive DMFC with an active membrane area of 9 cm(2), at ambient temperature and pressure. Results showed that the OCV of the passive DMFC became relatively stable as the cell temperature difference rose to a relatively stable value about 30 min later. At the middle and high current densities (>2.21 mA cm(-2)), the performance increased continuously with increasing the waiting time, but became stable when the waiting time was longer than 30 min. The experimental results indicated that the performance of the passive DMFC could be more objectively characterized by collecting polarization data simultaneously when the cell temperature rises to a relatively stable value. Without the temperature measuring equipment, a waiting time about 30 min would be a good choice for collecting polarization data.