The Experts below are selected from a list of 52245 Experts worldwide ranked by ideXlab platform
Shidong Song - One of the best experts on this subject based on the ideXlab platform.
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b4c as a stable non carbon based Oxygen Electrode material for lithium Oxygen batteries
Nano Energy, 2017Co-Authors: Shidong Song, Ruiguo Cao, Langli Luo, Mark H Engelhard, Mark E Bowden, Bin Liu, Luis Estevez, Chongmin Wang, Jiguang ZhangAbstract:Abstract Lithium-Oxygen (Li-O2) batteries have extremely high theoretical specific capacities and energy densities when compared with Li-ion batteries. However, the instability of both electrolyte and carbon-based Oxygen Electrode related to the nucleophilic attack of reduced Oxygen species during Oxygen reduction reaction and the electrochemical oxidation during Oxygen evolution reaction are recognized as the major challenges in this field. Here we report the application of boron carbide (B4C) as the non-carbon based Oxygen Electrode material for aprotic Li-O2 batteries. B4C has high resistance to chemical attack, good conductivity, excellent catalytic activity and low density that are suitable for battery applications. The electrochemical activity and chemical stability of B4C are systematically investigated in an aprotic electrolyte. Li-O2 cells using B4C-based air Electrodes exhibit better cycling stability than those using carbon nanotube- and titanium carbide-based air Electrodes in the electrolyte of 1 M lithium trifluoromethanesulfonate in tetraglyme. The performance degradation of B4C-based Electrode is mainly due to the loss of active sites on B4C Electrode during cycles as identified by the structure and composition characterizations. These results clearly demonstrate that B4C is a very promising alternative Oxygen Electrode material for aprotic Li-O2 batteries. It can also be used as a standard Electrode to investigate the stability of electrolytes.
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complete decomposition of li2co3 in li o2 batteries using ir b4c as noncarbon based Oxygen Electrode
Nano Letters, 2017Co-Authors: Shidong Song, Langli Luo, Mark H Engelhard, Mark E Bowden, Bin Liu, Chongmin Wang, Jianming Zheng, Jiguang ZhangAbstract:Instability of carbon-based Oxygen Electrodes and incomplete decomposition of Li2CO3 during charge process are critical barriers for rechargeable Li–O2 batteries. Here we report the complete decomposition of Li2CO3 in Li–O2 batteries using the ultrafine iridium-decorated boron carbide (Ir/B4C) nanocomposite as a noncarbon based Oxygen Electrode. The systematic investigation on charging the Li2CO3 preloaded Ir/B4C Electrode in an ether-based electrolyte demonstrates that the Ir/B4C Electrode can decompose Li2CO3 with an efficiency close to 100% at a voltage below 4.37 V. In contrast, the bare B4C without Ir electrocatalyst can only decompose 4.7% of the preloaded Li2CO3. Theoretical analysis indicates that the high efficiency decomposition of Li2CO3 can be attributed to the synergistic effects of Ir and B4C. Ir has a high affinity for Oxygen species, which could lower the energy barrier for electrochemical oxidation of Li2CO3. B4C exhibits much higher chemical and electrochemical stability than carbon-base...
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bifunctional Oxygen Electrode with corrosion resistive gas diffusion layer for unitized regenerative fuel cell
Electrochemistry Communications, 2006Co-Authors: Shidong Song, Huamin Zhang, Zhigang Shao, Yining Zhang, Baolian YiAbstract:To develop the unitized regenerative fuel cell (URFC) with low cost and high performance, a novel bifunctional Oxygen Electrode with a thin-film electrocatalyst layer and a corrosion-resistive gas diffusion layer (GDL) prepared by the carbon paper backing and a protective micro-porous layer (MPL) was developed. The protective MPL was made of the IrO2 deposited fine Ti powders. The cycle performance and polarization curves for both fuel cell and water electrolysis modes of URFC operation were investigated. The cycle performance of the URFC was stable during 20 cycles. It exhibits a high fuel cell performance as good as the URFC using the conventional GDL and a much higher water electrolysis performance. � 2006 Elsevier B.V. All rights reserved.
Scott A Barnett - One of the best experts on this subject based on the ideXlab platform.
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conditions for stable operation of solid oxide electrolysis cells Oxygen Electrode effects
Energy and Environmental Science, 2019Co-Authors: Beomkyeong Park, Qian Zhang, Peter W Voorhees, Scott A BarnettAbstract:Solid oxide electrolysis cells (SOECs) convert renewable electricity to fuels with efficiency substantially higher than other electrolysis technologies. However, questions remain regarding degradation mechanisms that limit SOEC long-term stability. One of the key degradation mechanisms is Oxygen Electrode delamination; although prior studies have improved the understanding of this mechanism, it is still difficult to predict how degradation depends on SOEC materials and operating conditions, i.e., temperature, voltage, and current density. Here we present a study aimed at developing a quantitative understanding of Oxygen Electrode delamination. Experimentally, a life test study of symmetric and full cells with yttria-stabilized zirconia (YSZ) electrolytes and Gd-doped ceria (GDC) barrier layers was done with three different perovskite Oxygen Electrode materials. Fracture was observed at the perovskite–GDC interface above a critical current density and below a critical operating temperature. A theory is presented that combines a calculation of the effective Oxygen pressure across the electrolyte with an estimation of the pressure required for fracture. Fracture is correctly predicted for a critical Oxygen partial pressure of ∼7200 atm and an associated Electrode overpotential of ∼0.2 V, occurring at the Electrode/GDC interface because of the relatively low perovskite fracture toughness. Damage at the GDC/YSZ interface was also observed in some cases and explained by a peak in the Oxygen pressure at this interface.
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cobalt substituted srti0 3fe0 7o3 δ a stable high performance Oxygen Electrode material for intermediate temperature solid oxide electrochemical cells
Energy and Environmental Science, 2018Co-Authors: Shan Lin Zhang, Hongqian Wang, Ai Ping Zhang, Liliana Veronica Mogni, Qinyuan Liu, Scott A BarnettAbstract:A key need in the development of solid oxide cells (SOCs) is for Electrodes that promote fast Oxygen reduction and Oxygen evolution reactions at reduced operating temperature (≤700 °C), with sufficient durability to allow operation over desired 40 000 h lifetimes. A wide range of Electrode materials have been investigated, with some providing resistance low enough for cell operation below 700 °C, but it is generally found that the Electrode performance degrades over time. Here we demonstrate an Oxygen Electrode material, Sr(Ti0.3Fe0.7−xCox)O3−δ (STFC), that provides a unique combination of excellent Oxygen Electrode performance and long-term stability. The addition of a relatively small amount of Co to Sr(Ti0.3Fe0.7)O3−δ, e.g., x = 0.07, reduces the Electrode polarization resistance by >2 times. The STFC Electrode yields stable performance in both fuel cell and electrolysis modes at 1 A cm−2. The fundamental Oxygen diffusion and surface exchange coefficients of STFC are determined, and shown to be substantially better than those of La0.6Sr0.4Co0.2Fe0.8O3−δ, the most widely used SOC Oxygen Electrode material. While other Electrode materials have been shown to exhibit better Oxygen transport coefficients than STFC, they do not match its stability.
Jiguang Zhang - One of the best experts on this subject based on the ideXlab platform.
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b4c as a stable non carbon based Oxygen Electrode material for lithium Oxygen batteries
Nano Energy, 2017Co-Authors: Shidong Song, Ruiguo Cao, Langli Luo, Mark H Engelhard, Mark E Bowden, Bin Liu, Luis Estevez, Chongmin Wang, Jiguang ZhangAbstract:Abstract Lithium-Oxygen (Li-O2) batteries have extremely high theoretical specific capacities and energy densities when compared with Li-ion batteries. However, the instability of both electrolyte and carbon-based Oxygen Electrode related to the nucleophilic attack of reduced Oxygen species during Oxygen reduction reaction and the electrochemical oxidation during Oxygen evolution reaction are recognized as the major challenges in this field. Here we report the application of boron carbide (B4C) as the non-carbon based Oxygen Electrode material for aprotic Li-O2 batteries. B4C has high resistance to chemical attack, good conductivity, excellent catalytic activity and low density that are suitable for battery applications. The electrochemical activity and chemical stability of B4C are systematically investigated in an aprotic electrolyte. Li-O2 cells using B4C-based air Electrodes exhibit better cycling stability than those using carbon nanotube- and titanium carbide-based air Electrodes in the electrolyte of 1 M lithium trifluoromethanesulfonate in tetraglyme. The performance degradation of B4C-based Electrode is mainly due to the loss of active sites on B4C Electrode during cycles as identified by the structure and composition characterizations. These results clearly demonstrate that B4C is a very promising alternative Oxygen Electrode material for aprotic Li-O2 batteries. It can also be used as a standard Electrode to investigate the stability of electrolytes.
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complete decomposition of li2co3 in li o2 batteries using ir b4c as noncarbon based Oxygen Electrode
Nano Letters, 2017Co-Authors: Shidong Song, Langli Luo, Mark H Engelhard, Mark E Bowden, Bin Liu, Chongmin Wang, Jianming Zheng, Jiguang ZhangAbstract:Instability of carbon-based Oxygen Electrodes and incomplete decomposition of Li2CO3 during charge process are critical barriers for rechargeable Li–O2 batteries. Here we report the complete decomposition of Li2CO3 in Li–O2 batteries using the ultrafine iridium-decorated boron carbide (Ir/B4C) nanocomposite as a noncarbon based Oxygen Electrode. The systematic investigation on charging the Li2CO3 preloaded Ir/B4C Electrode in an ether-based electrolyte demonstrates that the Ir/B4C Electrode can decompose Li2CO3 with an efficiency close to 100% at a voltage below 4.37 V. In contrast, the bare B4C without Ir electrocatalyst can only decompose 4.7% of the preloaded Li2CO3. Theoretical analysis indicates that the high efficiency decomposition of Li2CO3 can be attributed to the synergistic effects of Ir and B4C. Ir has a high affinity for Oxygen species, which could lower the energy barrier for electrochemical oxidation of Li2CO3. B4C exhibits much higher chemical and electrochemical stability than carbon-base...
Sunju Song - One of the best experts on this subject based on the ideXlab platform.
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performance of la0 1sr0 9co0 8fe0 2o3 δ and la0 1sr0 9co0 8fe0 2o3 δ ce0 9gd0 1o2 Oxygen Electrodes with ce0 9gd0 1o2 barrier layer in reversible solid oxide fuel cells
Journal of Power Sources, 2013Co-Authors: M B Choi, Bhupendra Singh, Eric D Wachsman, Sunju SongAbstract:Abstract La0.1Sr0.9Co0.8Fe0.2O3−δ (LSCF1982) and La0.1Sr0.9Co0.8Fe0.2O3−δ–Ce0.9Gd0.1O2 (LSCF1982–GDC) composite Oxygen Electrodes with a GDC barrier layer are tested in yttria stabilized zirconia (YSZ) electrolyte-based reversible solid oxide cells (RSOCs). Three button cell assemblies (1: NiO–YSZ|YSZ/GDC|LSCF1982; 2: NiO–YSZ/NiO–YSZ|YSZ/GDC|LSCF1982; and 3: NiO–YSZ/NiO–YSZ|YSZ/GDC|LSCF1982–GDC) are fabricated and their performance in solid oxide fuel cell (SOFC) and solid oxide electrolysis cell (SOEC) modes are studied at different temperatures (600 ≤ T/°C ≤ 800). The use of porous NiO–YSZ functional layer between hydrogen Electrode and electrolyte leads to improvements in SOFC and SOEC (SOFC/SOEC) performance by improving the diffusion of reacting species inside the Electrode. The effect of nature of Oxygen Electrode on SOFC/SOEC performance is studied, which indicates LSCF1982 Oxygen Electrode gives better performance than LSCF1982–GDC composite Oxygen Electrode, but LSCF1982–GDC composite Oxygen Electrode is more durable during reversible SOFC/SOEC operations. Stability of the button cells is studied in galvanostatic SOEC operation for 72 h and in reversible SOFC/SOEC operations. Current–voltage (I–V) tests and Electrochemical Impedance Spectroscopy (EIS) measurements indicate that the button cells show stable operation in SOEC mode. But successive SOFC → SOEC → SOFC operations indicate that the cells are not completely reversible. The possible reason for poor reversibility is found to be related with the grain growth in LSCF1982-based Oxygen Electrodes.
Dennis Y C Leung - One of the best experts on this subject based on the ideXlab platform.
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a computational study of bifunctional Oxygen Electrode in air breathing reversible microfluidic fuel cells
International Journal of Hydrogen Energy, 2011Co-Authors: Jin Xuan, Dennis Y C Leung, Michael K.h. Leung, Huizhi WangAbstract:Air-breathing reversible microfluidic fuel cell (RMFC) provides flexibility to choose either acid or alkaline medium for the bifunctional Oxygen Electrode. A numerical model has been developed and validated to predict the performance of an air-breathing RMFC. Half-cell J–V characteristics of the RMFC using different pH media for the Oxygen Electrode are compared. The model results suggest that when the RMFC is operated in fuel cell (FC) mode, alkaline medium is preferred for the Oxygen Electrode, and when operated in electrolysis-cell (EC) mode, acid medium is preferred. By further analyzing the round-trip energy efficiency and major potential loss of the half-cell, it is found that adopting acid medium for Oxygen Electrode can maximize the overall charging/discharging cycle efficiency and performance of RMFC, due to much lower activation overpotential in the EC mode. Heat and mass transport characteristics of the half-cell are also investigated. It is found that the flowing electrolyte can efficiently remove the heat generated by various sources in the RMFC, leading to the mass convection in the Oxygen Electrode and surrounding environment solely driven by concentration gradient. Due to the presence of water vapor as the reaction product, FC mode operation in acid medium yields the most intensive breathing process of the Oxygen Electrode. The results provide implications to further optimizations of RMFC.
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A modeling study on concentration overpotentials of a reversible solid oxide fuel cell
Journal of Power Sources, 2006Co-Authors: Meng Ni, Michael K.h. Leung, Dennis Y C LeungAbstract:A single reversible solid oxide fuel cell (RSOFC) can perform dual functions: (1) as a solid oxide steam electrolyzer (SOSE) for hydrogen production and (2) as a solid oxide fuel cell (SOFC) for power generation. Thus, RSOFC can potentially offer a low-cost approach to support hydrogen economy. A modeling study has been conducted to analyze the important concentration overpotentials in both SOSE and SOFC modes of operation. The quantitative analyses show that in the SOSE mode, the hydrogen Electrode is vulnerable to high concentration overpotential and limiting current density. Oppositely, in the SOFC mode, the Oxygen Electrode is vulnerable to above problems. If the SOSE and SOFC modes are considered separately, a RSOFC should be Oxygen-Electrode-supported and hydrogen-Electrode-supported, respectively. For this reason, comprehensive analysis is very important to optimize the structure of the Electrode-support to maximize the overall efficiency of a RSOFC performing dual functions. The modeling study signifies the difference between the SOSE and SOFC modes and provides insights in the operating mechanisms of RSOFC. The present model can be further extended to conduct more simulations for design optimization.
