• Korean Chemical Engineering Research
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• v.62 no.1
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• pp.7-12
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• 2024

The durability of the catalyst support has a significant effect on the durability of proton exchange membrane fuel cells (PEMFC). The accelerated durability evaluation of the catalyst support is performed at a high voltage (1.0 to 1.5 V), and the catalyst and ionomer binder in the catalyst layer are also deteriorated, hindering the evaluation of the durability of the support. The existing protocol (DOE protocol) was improved to find conditions in which the support, which is a durability evaluation target, deteriorates further. A protocol (MDOE) was developed in which the relative humidity was lowered by 35% and the number of voltage changes was reduced. After repeating the 1.0 ↔ 1.5 V voltage change cycle, the catalyst mass activitiy (MA), electrochemical active area (ECSA), electrical double layer capacity (DLC), Pt dissolution and particle growth were analyzed. Reaching 40% reduction in mass activity, the MDOE protocol took only 500 cycles, reducing the number of voltage changes compared to the DOE method and increasing the degradation of the carbon support by 50% compared to the DOE protocol.

• Applied Chemistry for Engineering
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• v.35 no.4
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• pp.309-315
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• 2024

Silicon and carbon composite (SiC) is considered one of the most promising anode materials for the commercialization of Si-based anodes, as it could simultaneously satisfy the high theoretical capacity of Si and the high electronic conductivity of carbon. However, SiC active material undergoes repeated volumetric changes during charge/discharge processes, leading to continuous electrolyte decomposition and capacity fading, which is still considered an issue that needs to be addressed. To solve this issue, we suggest a 4,4'-Methylenebis(cyclohexyl isocyanate) (H₁₂MDI)-based waterborne polyurethane binder (HPUD), which forms a 3D network structure through thermal cross-linking reaction. The cross-linked HPUD (denoted as CHPU) was prepared using an epoxy ring-opening reaction of the cross-linker, triglycidyl isocyanurate (TGIC), via simple thermal treatment during the SiC anode drying process. The SiC anode with the CHPU binder, which exhibited superior mechanical and adhesion properties, not only demonstrated excellent rate and cycling performance but also alleviated the volume expansion of the SiC anode. This work implies that eco-friendly binders with cross-linked structures could be utilized for various Si-based anodes.

• Membrane Journal
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• v.27 no.4
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• pp.344-349
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• 2017

Alkaline fuel cells using polymer electrolyte membranes are expected to replace proton exchange membrane fuel cells, which have similar system configurations. In particular, in alkaline fuel cells, a low-cost non-platinium catalyst can be used. In this study, to fabricate high performance and high durability anion exchange membranes for alkaline fuel cell systems, two kinds of supports, polybenzoxazole and polyethylene supports, were impregnated with Fumion FAA ionomer, by which we tried to fabricate the support-impregnated membrane which has higher mechanical strength and higher ion conductivity than the Fumion series. Finally, the Pore-filling membranes were successfully fabricated and ionic conductivity and mechanical properties were different depending on the properties of the supports. In the pore-filling membranes with Fumion ionomer on the PE support, excellent mechanical properties were obtained, but ionic conductivity decreased. On the other hand, when the PBO support was impregnated with Fumion ionomer, high ionic conductivity was shown after impregnation due to high basicity of PBO, but the mechanical strength was relatively low as compared with Fumion-PE membrane. As a result, it was concluded that it is necessary to consider the characteristics of the support according to the operating conditions of the alkaline fuel cell during the preparation of the pore-filling membranes.

• Korean Chemical Engineering Research
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• v.45 no.6
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• pp.656-662
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• 2007

Fuel reformer using plasma and shift reactor for CO oxidation were designed and manufactured as $H_2$ supply device to operate a polymer electrolyte membrane fuel cell (PEMFC). $H_2$ selectivity was increased by non-thermal plasma reformer using GlidArc discharge with Ni catalyst simultaneously. Shift reactor was consisted of steam generator, low temperature shifter, high temperature shifter and preferential oxidation reactor. Parametric screening studies of fuel reformer were conducted, in which there were the variations of the catalyst temperature, gas component ratio, total gas ratio and input power. and parametric screening studies of shift reactor were conducted, in which there were the variations of the air flow rate, stema flow rate and temperature. When the $O_2/C$ ratio was 0.64, total gas flow rate was 14.2 l/min, catalytic reactor temperature was $672^{\circ}C$ and input power 1.1 kJ/L, the production of $H_2$ was maximized 41.1%. And $CH_4$ conversion rate, $H_2$ yield and reformer energy density were 88.7%, 54% and 35.2% respectively. When the $O_2/C$ ratio was 0.3 in the PrOx reactor, steam flow ratio was 2.8 in the HTS, and temperature were 475, 314, 260, $235^{\circ}C$ in the HTS, LTS, PrOx, the conversion of CO was optimized conditions of shift reactor using simulated reformate gas. Preheat time of the reactor using plasma was 30 min, component of reformed gas from shift reactor were $H_2$ 38%, CO<10 ppm, $N_2$ 36%, $CO_2$ 21% and $CH_4$ 4%.