Fuel Cells: Advances and Challenges

Wang, Xin

doi:10.1002/9783527635566.ch5

Cited by 8 publications

(7 citation statements)

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“…Fuel cells represent a promising technology for clean power generation, because they convert chemical energy (fuel) into electrical energy with high efficiency and little to no emission of pollutants. − Direct ethanol fuel cells (DEFCs) have several advantages, compared to the most studied hydrogen and methanol fuel cells. First and foremost, ethanol is a nontoxic liquid, which reduces the investment of handling facilities because the current infrastructure for gasoline can be largely used. , Second, ethanol can be conveniently produced from biomass; hence, it is carbon neutral, which mitigates increasing atmospheric CO 2 .…”

Section: Introductionmentioning

confidence: 99%

Ethanol Electro-oxidation on Palladium Revisited Using Polarization Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS) and Density Functional Theory (DFT): Why Is It Difficult To Break the C–C Bond?

et al. 2016

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International audienceInsights into the ethanol electro-oxidation reaction mechanism on palladium in alkaline media are presented combining polarization modulation infrared reflec- tion absorption spectroscopy (PM-IRRAS) and density functional theory (DFT) calculations. The synergy between PM-IRRAS and DFT calculations helps to explain why the C− C bond is not broken during ethanol electro-oxidation, and the reaction stops at acetate. Coupling chronoamperometry (CA) with in situ PM-IRRAS enables us to simultaneously identify ethanol electro-oxidation products on the catalyst surface and in the bulk solution. We show that, at lower potential, it is possible to break the C−C bond on Pd/C in alkaline media to form CO2. However, the selectivity is poor, because of competition with the formation of acetate and other side products, which gets worse at higher potentials. DFT computations complete the picture using the computational hydrogen electrode approach. The computations highlight the pivotal role of the CH3CO intermediate that can either undergo a C−C bond scission yielding CO and then CO2 or that can be oxidized toward CH3COO−. The latter is a dead end in the reaction scheme toward CO2 production, since it cannot be easily oxidized nor broken into C1 fragments. However, CH3CO is not the most favored intermediate formed from ethanol electro-oxidation on Pd, hence limiting the production of CO2

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Section: Introductionmentioning

confidence: 99%

Ethanol Electro-oxidation on Palladium Revisited Using Polarization Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS) and Density Functional Theory (DFT): Why Is It Difficult To Break the C–C Bond?

et al. 2016

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“…Solid oxide fuel cells (SOFCs) are an energy conversion device to directly convert the chemical energy of fuels such as hydrogen, natural gas, and hydrocarbons to electrical energy. SOFCs with combined power and heat have a high efficiency of 70–90% and are environmentally friendly with much less CO 2 emission when compared to direct combustion . In the case of intermediate temperature SOFCs with operation temperature of 600–800 °C, the performance and power output of the cell depend strongly on the electrocatalytic activity of electrode materials of anode and cathode.…”

Section: Introductionmentioning

confidence: 99%

“…SOFCs with combined power and heat have a high efficiency of 70−90% and are environmentally friendly with much less CO 2 emission when compared to direct combustion. 1 In the case of intermediate temperature SOFCs with operation temperature of 600−800 °C, the performance and power output of the cell depend strongly on the electrocatalytic activity of electrode materials of anode and cathode. La 0.8 Sr 0.2 MnO 3+δ (LSM) is the most common cathode for high-temperature SOFCs but performs poorly at reduced temperatures because it is a predominantly electronic conductor with negligible ionic conductivity and its activation energy for the O 2 reduction reaction is high.…”

Section: Introductionmentioning

confidence: 99%

Polarization-Induced Interface and Sr Segregation of in Situ Assembled La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ Electrodes on Y₂O₃–ZrO₂ Electrolyte of Solid Oxide Fuel Cells

Chen

Ai³

et al. 2016

ACS Appl. Mater. Interfaces

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Application of cobaltite-based electrodes such as LaSrCoFeO (LSCF) on YO-ZrO (YSZ) electrolyte in solid oxide fuel cells (SOFCs) generally requires the use of a doped ceria barrier layer to prevent the interaction between LSCF and YSZ during sintering at high temperatures. In this paper, we report for the first time an in situ assembly approach to directly incorporate LSCF cathode to YSZ electrolyte without the use of a doped ceria barrier layer and without presintering at high temperatures. A Ni-YSZ anode-supported YSZ electrolyte cell with an in situ assembled LSCF electrode exhibits a peak power density of 1.72 W cm at 750 °C. However, the cell performance degrades significantly at 500 mAcm and 750 °C. The results indicate that cathodic polarization not only induces the formation of the interface but also accelerates the Sr segregation. The segregated Sr migrates to the LSCF electrode/YSZ electrolyte surface and forms an SrO layer. Using a Sr-free LaCoO composite cathode overcomes the Sr segregation problem, showing an excellent peak power density of 1.2 Wcm and good stability at 750 °C for over 100 h. The present study shows that cobaltite-based perovskites can be directly used on YSZ-based electrolyte via the in situ assembly providing an effective means to advance the application of highly active mixed ionic/electronic conducting cathodes to YSZ electrolyte-based SOFCs.

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“…The rapid growth in global energy demand in the face of dwindling global resources has been stimulating increasing efforts toward the development of high energy and high power batteries based on both lithium ion 1 and solid oxide fuel cell (SOFC) 2 technologies. Both processes utilize fast ion transport in the solid state at ambient or elevated temperatures.…”

Section: ■ Introductionmentioning

confidence: 99%

Glass-to-Crystal Transition in Li_1+xAl_xGe_2–x(PO₄)₃: Structural Aspects Studied by Solid State NMR

et al. 2014

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The structural aspects of the glass-to-crystal transition in the technologically important ion conducting glass ceramic system Li 1+x Al x Ge 2−x (PO 4 ) 3 (0 ≤ x ≤ 0.75) have been examined by complementary multinuclear solid state nuclear magnetic single and double-resonance experiments. In the crystalline state, the materials form solid solutions in the NASICON structure, with additional nanocrystalline AlPO 4 present at x values ≥0.5. Substitution of Al in the octahedral Ge sites results in a binomial distribution of multiple phosphate species, which differ in the number P−O−Al and P−O−Ge linkages and can be differentiated by 31 P double quantum NMR studies suggest that the AlO 6 coordination polyhedra are noticeably expanded compared to the GeO 6 sites in the NASICON-type LiGe 2 (PO 4 ) 3 (LGP) structure. While the glassy state is characterized by a significantly larger degree of disorder concerning the local coordination of germanium and aluminum, dipolar solid state NMR studies clearly indicate that their medium range structure is comparable to that in NASICON, indicating the dominance of P−O−Al and P−O−Ge over P− O−P and Al−O−Ge connectivities. ■ INTRODUCTIONThe rapid growth in global energy demand in the face of dwindling global resources has been stimulating increasing efforts toward the development of high energy and high power batteries based on both lithium ion 1 and solid oxide fuel cell (SOFC) 2 technologies. Both processes utilize fast ion transport in the solid state at ambient or elevated temperatures. During the past two decades a large number of crystalline and glassy fast ion conductors have been identified and thoroughly characterized, and excellent reviews on oxide and proton conductors for fuel cell applications, 3 as well as fast ion conductors for lithium batteries, are available.4−6 The highest lithium ion conductivities in the solid state are generally encountered in crystalline compounds with highly disordered cation sublattices, termed superionic crystals. On the other hand, ion conducting glasses are often preferred in practice as they do not suffer from grain boundary effects and form more homogeneous interfaces with the anode and cathode compartments of a solid state electrochemical cell. The favorable features of both the crystalline and the glassy state can be combined in an ideal way using ion conducting glass ceramics, and numerous promising systems presenting electrical conductivities in excess of 10 −3 (Ω·cm) −1 at room temperature have been developed. 7,8 One particularly attractive system is based on the crystallization of precursor glasses in the systems Li 2 O-MO 2 -Al 2 O 3 -P 2 O 5 (M = Ge, Ti). While the glasses themselves are poorly conducting, they crystallize in the NASICON structure, which features exceptionally high ionic conductivities.9−15 Their structure is derived from the phases MTi 2 (PO 4 ) 3 (M = Li, Na) and MGe 2 (PO 4 ) 3 , which feature octahedrally coordinated Ti 4+ and Ge 4+ cations linked through phosphate tetrahedra via corner sharing ...

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Fuel Cells: Advances and Challenges

Cited by 8 publications

References 433 publications

Ethanol Electro-oxidation on Palladium Revisited Using Polarization Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS) and Density Functional Theory (DFT): Why Is It Difficult To Break the C–C Bond?

Ethanol Electro-oxidation on Palladium Revisited Using Polarization Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS) and Density Functional Theory (DFT): Why Is It Difficult To Break the C–C Bond?

Polarization-Induced Interface and Sr Segregation of in Situ Assembled La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ Electrodes on Y₂O₃–ZrO₂ Electrolyte of Solid Oxide Fuel Cells

Glass-to-Crystal Transition in Li_1+xAl_xGe_2–x(PO₄)₃: Structural Aspects Studied by Solid State NMR

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Fuel Cells: Advances and Challenges

Cited by 8 publications

References 433 publications

Ethanol Electro-oxidation on Palladium Revisited Using Polarization Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS) and Density Functional Theory (DFT): Why Is It Difficult To Break the C–C Bond?

Ethanol Electro-oxidation on Palladium Revisited Using Polarization Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS) and Density Functional Theory (DFT): Why Is It Difficult To Break the C–C Bond?

Polarization-Induced Interface and Sr Segregation of in Situ Assembled La0.6Sr0.4Co0.2Fe0.8O3−δ Electrodes on Y2O3–ZrO2 Electrolyte of Solid Oxide Fuel Cells

Glass-to-Crystal Transition in Li1+xAlxGe2–x(PO4)3: Structural Aspects Studied by Solid State NMR

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Polarization-Induced Interface and Sr Segregation of in Situ Assembled La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ Electrodes on Y₂O₃–ZrO₂ Electrolyte of Solid Oxide Fuel Cells

Glass-to-Crystal Transition in Li_1+xAl_xGe_2–x(PO₄)₃: Structural Aspects Studied by Solid State NMR