Narrow Results

In order to improve the anti-corrosion performance of thin stainless steel bipolar plates of proton exchange membrane fuel cell (PEMFC), the carbon film (of about 0.82-$\mu$m thickness) was fabricated on the thin stainless steel by laser direct writing technology irradiating the formed dense polydopamine (PDA) film. The results indicated that the PDA film has partially transformed into nanocrystalline graphite. Laser power and scanning speed had great effect on the anti-corrosion performance of the final obtained film in simulated PEMFC environment. When the laser power is 3.5 W and the scanning speed is 10 mm/s, the film obtained on the thin stainless steel has the best electrochemical performance in simulated PEMFC environment. Its corrosion current densities were $8.64\mu$A $\cdot$ cm${}^{-2}$@ −0.1 V (versus SCE) and $1.33\mu$A $\cdot$ cm ${}^{-2}$@ 0.6 V (versus SCE) in simulated anode and cathode environments, respectively. Compared with the bare thin stainless steel, the corresponding corrosion current densities decreased by 45% and 62%. The results obtained in this text provide a novel strategy for modifyingPEMFC thin metal bipolar plates.

Sulfonated SiO₂ was added on an anode catalyst layer to manufacture a hygroscopic electrode for self-humidifying proton exchange membrane fuel cells (PEMFCs). The inherent humidity of a proton exchange membrane (PEM) determines the electrical performance of PEMFCs. To maintain the high moisture content of the PEM, self-humidifying PEMFCs can use the water produced by the fuel cell reaction and, thus, do not require external humidification. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and water contact angle measurement tests were performed to characterize the structures and properties of sulfonated SiO₂ and the related electrodes, and the electric current and voltage (I–V) performance curve tests for the fuel cells were conducted under differing gas humidification conditions. When 0.01mg/cm² of sulfonated SiO₂ was added, the electrical performance of the fuel cells (50${}^{\circ }$C) increased 29% and 59% when the fuel cell reaction gases were humidified at 70${}^{\circ }$C and 50${}^{\circ }$C, respectively.

There are many attempts to use a fuel cell system as a residential power generation system. The purpose of this study is to investigate the optimal design of a water tank for a hot water system when the fuel cell co-generation system is combined with a domestic hot water supply system. The demands of hot water supply per month per home for 76–168 m² of acreage are investigated in Busan for a year. It showed somewhat large differences between the actual demand and the designed demand of hot water, but the actual capacity of hourly averaged hot water demands is analyzed as 60 ℓ/h in this study based on the actual demand. The experiments are performed in the various inlet and outlet locations of nozzles in the hot water tank, and the hot water consumption rates. The experimental results showed that the optimal capacity of the water tank is 200 ℓ when the thermal efficiency, the storing capacity of hot water and the space for installation are considered.

Stainless steels are attractive due to its high strength, high chemical stability, low gas permeability and wide selection of alloys. However, stainless steels are prone to corrosion where SO4^2- and F^- are released from the membrane in the PEFCs, which, as a result, will shorten the age of the bipolar plates and exert a negative influence on the function of the cells. Therefore, great attention is given on high-nitrogen austenitic stainless steels (HNASS) which have lower costs and good localized corrosion resistance. The effects of the different F- concentration on the corrosion behavior in the high nitrogen austenitic stain steel were investigated through polarization curve measurement and electrochemical impedance spectroscopy. The results show that the corrosion resistance of the experimental steel is the best in the 0.05 mol/L SO42- (pH 5.5) + 2 ppm F- solution. As the F- concentration increases, the passivation film of the experimental steel becomes thicker and denser, leading to stronger corrosion resistance.