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Abstract: A new anion exchange membrane was synthesized by a green and facile route---chemically grafting polybenzimidazole (PBI) membrane with BrCH2CH3. The obtained membrane was characterized by means of ex-situ and in-situ tests (EDX, FTIR, AC impedance, single cell test and so on). The results suggested that the group of –CH2CH3 was successfully grafted onto N atom within PBI backbone, while with Br− as counter ion. The corresponding ionic conductivity and ethanol permeability were about 0.022 Scm−1 and 5.24 × 10−8 cm2s−1, respectively. Finally, single cell test suggested that air-breathing alkaline direct ethanol fuel cell with quaternized PBI membrane can deliver a peak power density of about 11 mWcm−2 even at ambient temperature of 13 °C, which was better than those of air-breathing alkaline direct methanol fuel cell in literatures. In addition, a possible reaction mechanism was also proposed and discussed. [Copyright &y& Elsevier]

Abstract: In this paper, the reversible and the irreversible loss in performance of direct methanol fuel cell (DMFC) single cells induced by freeze/thaw cycling are determined and discussed. The reversible loss in performance is attributed to the decreased activity of electrocatalysts due to the strong adsorption of the intermediates from methanol electro-oxidation at subzero temperatures, while the irreversible loss in performance is due to the damage of membrane electrode assembly (MEA) structure. It is found that the reversible degradation of performance is dominant when the cell operated at low current densities with O2; the irreversible degradation is more obvious when the cell discharged at high current densities or operated with air. A method, applying a reverse current on the single cell, is put forward to recover the reversible loss in performance. By this method, the voltage of the single cell operated with O2 at 100 mA cm−2 drops only about 16 mV after experiencing 100 freeze/thaw cycles between−10 and 60 °C. [Copyright &y& Elsevier]

Abstract: In this work, an integrated catalyst-coated membrane (CCM) is prepared by successively spray deposit Pt/C nano-suspension, Nafion solution and Pt–Ru/C nano-suspension on a cathode gas diffusion layer using electrohydrodynamic atomization (EHDA) Layer-by-Layer (LbL) deposition. Porous cathode and anode catalyst layers and dense Nafion membrane are deposited using the EHDA LbL deposition technique. It is also found that the EHDA LbL deposited CCM presents close packed structure. An 85 h life test shows that the EHDA LbL deposited cathode electrode side of the integrated CCM still presents well compact feature. Whereas, the delamination of the anode electrode side formed by direct pressing method is evident. The performance of the cell with different methanol concentrations is also examined. It is found that the 3 M methanol concentration gives the highest cell performance. Moreover, the polarization behaviour, methanol crossover and impedance response of the cell at different working temperatures are analysed. The cell performance demonstrates faster increase between 20 °C and 50 °C than between 50 °C and 70 °C. The methanol crossover test shows that the cell presents higher increase level of methanol crossover between 40 °C and 50 °C than other 10 °C temperature increase steps. [Copyright &y& Elsevier]