Influencing Factors on the Stability of Direct Methanol Fuel Cells

Abstract

This work investigated the influencing factors on the stability of direct methanol fuel cells via testing a single-cell, which was conducted at 60°C under 100 mA cm -2 for 3,009 h. To completely uncover and interpret the performance degradation mechanism, electrochemical method (such as polarization curve, electrochemical impedance spectra, anode polarization voltammetry, methanol crossover and cyclic voltammetry tests), electron microscopy technique (SEM, TEM and EDX) and XRD spectroscopy were coherently performed in this work. The degradation rate in the whole test process is relatively steady, in which the cell voltage decreases 29% and the maximum power density decreases 35%. However, there is obviously an irreversible degradation when the cell runs at about 1,600 h. According to our analysis, the irreversible degradation of the cell is mainly caused by the increase of resistance and decrease of catalytic activity. Further, the increase of the resistance might be due to the increase of the interface resistance between cathode and Nafion membrane according to SEM results. In addition, the decrease of catalytic activity is mostly caused by Ru loss from anode side to cathode side and the agglomeration of catalyst particles in both electrodes.

Effect of the Anode Structure on the Stability of a Direct Methanol Fuel Cell

“…The micropore layer (MPL) of the gas diffusion layer (GDL) consists of the carbon paper (Toray paper TGPH 060), Vulcan XC-72 carbon powder, acetylene black (AB) carbon powder, and PTFE. The preparation of the MPL is same as that in our previous paper …”

“…Anode polarization voltammetry (APV), electrochemical impedance spectroscopy (EIS), methanol crossover voltammetry (MCV), methanol stripping voltammetry (MSV), and cyclic voltammogram (CV) measurements were performed at 0, 1000, 2000, 3000, and 4000 h during the stability tests. SL model 1287 and SL model 1260 were used to accomplish these electrochemical measurements …”

“…EIS was undertaken to measure and inspect the internal resistance (IR) variation of the DMFCs during the stability test. The EIS was performed during the stability test, and the test method was the same as that of our previous work …”

Polypyrrole nanowires as a cathode microporous layer for direct methanol fuel cell to enhance oxygen transport

“…17 Therefore, the optimal PTFE loading was 40, 30 and 60 wt% PTFE loadings were also used to fabricate the cathode MPL for DMFC. 18,19 The adoption of high PTFE loading is to accelerate the removal of water. If not removed, the accumulated water can block oxygen transfer and cause water flooding problems.…”

“…Zhao and coworkers found when the PTFE content increased from 20 to 40 wt%, DMFC performance improved, but the performance decreased when the content increased to 50 wt% 17 . Therefore, the optimal PTFE loading was 40, 30 and 60 wt% PTFE loadings were also used to fabricate the cathode MPL for DMFC 18,19 . The adoption of high PTFE loading is to accelerate the removal of water.…”