Improvement Of Dmfc Performance And Stability Using Multi-Layer Structure Membranes

Multi-layer structure membranes composed of a central methanol barrier layer and two high proton conductive surface layers were developed to suppress methanol crossover in direct methanol fuel cells (DMFC). Sulfonated poly(ether ether ketone) (SPEEK) membranes with lower sulfonation degree (SD = 41%) were used as the methanol barrier layer; while higher SD SPEEK membranes or Nafion® were applied on both surfaces. SPEEK membranes with a sulfonation degree of 40-60% showed good potential for DMFC applications. DMFC performance of pure SPEEK membrane with higher sulfonation degree (SD = 60%) decreased as temperature was increased from 60° to 80°C due to greatly increased methanol crossover, which was induced by severe membrane swelling in the methanol solution. The multi-layer structure membranes lowered methanol crossover because the central barrier layer had much less swelling in methanol solution and effectively blocked methanol crossover. The DMFC performance and stability was significantly improved by using the multi-layer structure membrane. This is an abstract of a paper presented at the 230th ACS National Meeting (Washington, DC 8/28/2005-9/1/2005)