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J. Electrochem. En. Conv. Stor.. 2017;14(4):041001-041001-9. doi:10.1115/1.4036956.

The potential of an energy system that comprises hydrogen-fueled polymer electrolyte fuel cells (PEFCs), a steam reformer, and a hydrogen storage tank, using surplus hydrogen produced from an oil refinery, was evaluated using a mathematical model based on linear programming. The aim of this study was to optimize the capacity of the hydrogen-fueled PEFC, the hydrogen production of the steam reformer, and the utilization amount of the hydrogen storage tank in order to minimize the total system cost. Based on the optimization results, the system cost reduction and CO2 emission reduction effects were calculated in relation to the power generation efficiency and the installation cost of the hydrogen-fueled PEFC. As a result, the conditions for the hydrogen-fueled PEFC where a system cost reduction could be achieved in the PEFC power generation system, compared with the conventional system, were shown to be an initial cost lower than 3000 $/kW for a power generation efficiency of 50% or an initial cost lower than 5000 $/kW for a power generation efficiency of 65%.

Commentary by Dr. Valentin Fuster
J. Electrochem. En. Conv. Stor.. 2017;14(4):041002-041002-8. doi:10.1115/1.4037232.

The effects of isothermally long-term and thermal cycling tests on the performance of an ASC type commercial solid oxide fuel cell (SOFC) have been investigated. For the long-term test, the cells were tested over 5000 h in two stages, the first 3000 h and the followed 2000 h, under the different flow rates of hydrogen and air. Regarding the thermal cycling test, 60 cycles in total were also divided into two sections, the temperature ranges of 700 °C to 250 °C and 700 °C to 50 °C were applied for the every single cycle of first 30 cycles and the later 30 cycles, respectively. The results of long-term test show that the average degradation rates for the cell in the first 3000 h and the followed 2000 h under different flow rates of fuel and air are 1.16 and 2.64%/kh, respectively. However, there is only a degradation of 6.6% in voltage for the cell after 60 thermal cycling tests. In addition, it is found that many pores formed in the anode of the cell which caused by the agglomeration of Ni after long-term test. In contrast, the vertical cracks penetrating through the cathode of the cell and the in-plane cracks between the cathode and barrier layer of the cell formed due to the coefficient of thermal expansion (CTE) mismatch after 60 thermal cycling tests.

Commentary by Dr. Valentin Fuster
J. Electrochem. En. Conv. Stor.. 2017;14(4):041003-041003-7. doi:10.1115/1.4037391.

Flow field plays an important role in the performances of the fuel cells, especially in large area fuel cells. In the present work, an innovative, versatile flow field, capable of combining in different conventional modes is reported and evaluated in a polymer electrolyte fuel cell (PEFC) with an active area of 150 cm2. The proposed design is capable of offering serpentine, interdigitated, counterflow, dead-end, and serpentine-interdigitated hybrid mode. Moreover, it is possible to switch over from one flow mode to another mode of flow during operation at any point of time. The flow design consists of the multichannel parallel serpentine flow (SP) field and a pair of an inlet and outlet manifolds instead of conventional single inlet and outlet manifold. Flow distribution was successfully altered without affecting the performances, and it was observed a combination of serpentine and interdigitated on the cathode side offered steady performance for more than 20 min when it was operated at a current density of 700 mA cm−2.

Commentary by Dr. Valentin Fuster
J. Electrochem. En. Conv. Stor.. 2017;14(4):041004-041004-6. doi:10.1115/1.4037532.

In the present paper, a composite electrode material was developed for vanadium redox flow batteries (VRFBs). Activated charcoal particles were evenly immobilized on the graphite felt (GF) via a sucrose pyrolysis process for the first time. The in site formed pyrolytic carbon is used as the binder, because it is essentially carbon material as well as GF and activated charcoal, which has a natural tendency to realize good adhesion and low contact resistance. The activated charcoal decorated GF electrode (abbreviated as the composite electrode) possesses larger surface area (13.8 m2 g−1), more than two times as GF (6.3 m2 g−1). The oxygen content of composite electrode is also higher (7.0%) than that of GF (4.8%). The composite electrode was demonstrated to lower polarization and increase the reversibility toward the VO2+/VO2+ redox couple according to the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements. The charge–discharge cycling test was conducted with a single VRFB cell. The results indicate that the cell with composite electrode presents higher charge–discharge capacity, larger electrolyte utilization efficiency (EU), and higher energy conversion efficiency (79.1%) compared with that using GF electrode. The increasing electrochemical performances of composite electrodes are mainly ascribed to the high electrochemical activity of activated charcoal particles and increasing superficial area.

Commentary by Dr. Valentin Fuster
J. Electrochem. En. Conv. Stor.. 2017;14(4):041005-041005-8. doi:10.1115/1.4037491.

The large push for more environmental energy storage solutions for the automotive industry by different actors has led to the usage of lithium-ion capacitors (LICs) combining the features of both lithium-ion batteries (LIBs) and electric-double layer capacitors (EDLCs). In this paper, the thermal behavior of two types of advanced LICs has been thoroughly studied and analyzed by developing a three-dimensional (3D) thermal model in COMSOL Multiphysics®. Such an extensive and accurate thermal 3D has not been fully addressed in literature, which is a key building block for designing battery packs with an adequate thermal management. After an extensive measurement campaign, the high accuracy of the developed model in this paper is proven for two types of LICs, the 3300 F and the 2300 F. An error between the simulation and measurements is maximum 2 °C. This 3D model has been developed to gain insight in the thermal behavior of LICs, which is necessary to develop a thermal management system, which can ensure the safe operation of LICs when used in modules or packs.

Commentary by Dr. Valentin Fuster

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