Structure and Properties of Novel Cobalt-Free Oxides NdxSr1–xFe0.8Cu0.2O3−δ (0.3 ≤ x ≤ 0.7) as Cathodes of Intermediate Temperature Solid Oxide Fuel Cells

Yin, Jiewei; Yin, Yi; Lu, Jun; Zhang, Chunming; Minh, Nguyễn Quang; Ma, Zi-Feng

doi:10.1021/jp500371w

Cited by 105 publications

(40 citation statements)

References 72 publications

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“…By fitting the impedance spectra against an equivalent circuit model, one could deconvolute polarisation the ASR (R T ) into two resistances: R 1 resistance at higher frequency (10 21 0 5 Hz) related to charge-transfer process, and R 2 at lower frequency < 10 2 Hz related to non-charge-transfer process including adsorption, diffusion, and dissociation of the oxygen species. [6,42] Figure S7b shows that resistance R 2 is higher than R 1 for all the Li-doped samples, indicating that non-charge-transfer process is the rate-determining step at 600°C. It also revealed that at 600°C the SLFNT50 has the lowest R 2 and 2 nd lowest R 1 among all the Li-doped cathodes.…”

Section: Catalytic Activity For Orrmentioning

confidence: 94%

“…[6,42] Figure S7b shows that resistance R 2 is higher than R 1 for all the Li-doped samples, indicating that non-charge-transfer process is the rate-determining step at 600°C. [6,42] Figure S7b shows that resistance R 2 is higher than R 1 for all the Li-doped samples, indicating that non-charge-transfer process is the rate-determining step at 600°C.…”

Section: Catalytic Activity For Orrmentioning

confidence: 97%

“…Generally, the electrical conductivity comprises of both electronic and ionic conductivities, with the electronic conductivity dominating the overall conductivity. [22,[41][42] Figure 6a shows that all the oxides follow a typical semi-conductor behavior at temperatures lower than 525°C (i. e. σ increases with temperature), and a metallic conducting behavior at higher temperatures (i. e. σ decreases with temperature). [31,43] The linear relationship between ln(Tσ) and 1/T at temperatures below 525°C as presented in Figure 6b indicates that all the tested oxides underwent a thermally activated polaron hopping mechanism.…”

Section: Oxygen Vacancies and Electrical Conductivitymentioning

confidence: 99%

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Unveiling Lithium Roles in Cobalt‐Free Cathodes for Efficient Oxygen Reduction Reaction below 600 °C

Rehman

Knibbe

et al. 2019

ChemElectroChem

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Improving the sluggish electrocatalytic oxygen reduction reaction (ORR) over cobalt-free cathodes at 550-800°C is imperative to circumvent challenges faced by practical operation of intermediate temperature solid oxide fuel cells. In this work, we synthesize novel cobalt-free, lithium (Li)-doped, perovskite oxides Sr 1-x Li x Fe 0.8 Nb 0.1 Ta 0.1 O 3-δ (SLFNTx, x = 0-0.1) as cathodes for efficient ORR catalysis. When the Li concentration is less than 0.05, ORR activity is enhanced by over 1.6-fold in comparison to the undoped SFNT below 600°C in both symmetrical and anode-supported single cells configurations. Our comprehensive investigation over crystal structure, surface, and mixed conductivities revealed that a moderate concentration (< 0.05) of Li could bestow the perovskite with a stable cubic perovskite structure that contains an optimal concentration of oxygen vacancies and A-site deficiencies. Such trend originates from the lower electronegativity and smaller size of Li dopant than the strontium host. The lower electronegativity increases oxygen vacancies. The small Li dopant induces thermal-migration of Li species and creates A-site deficiency. These insights highlight an effective strategy to advance the performance of cobalt-free ORR electrocatalyst below 600°C through in situ thermal surface migration of the A-site cations.

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Section: Catalytic Activity For Orrmentioning

confidence: 94%

Section: Catalytic Activity For Orrmentioning

confidence: 97%

Section: Oxygen Vacancies and Electrical Conductivitymentioning

confidence: 99%

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Unveiling Lithium Roles in Cobalt‐Free Cathodes for Efficient Oxygen Reduction Reaction below 600 °C

Rehman

Knibbe

et al. 2019

ChemElectroChem

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“…Several studies have concentrated on different perovskite-based materials and oxide combinations, that could result in more efficient cathodes in the intermediate temperature range of 500-800°C [3][4][5][6]. In this study we have focused on the Ce 1/3 NbO 3 compound, which is a member of the series Ln 1/3 NbO 3 (Ln = rare earth).…”

Section: Introductionmentioning

confidence: 99%

On the mechanism of electrical conductivity in Ce 1/3 NbO 3

Gómez-García

Ramírez-de-Arellano

Ruiz‐Trejo

et al. 2016

Computational Materials Science

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a b s t r a c tUsing electrical conductivity measurements, we found the existence of different activation energy values for the electric transport in Ce 1/3 NbO 3 : 0.78 eV for T > 800°C and 0.39 eV for T < 800°C. Atomistic simulations have shown that the energy required to move the Ce 3+ ions is around 8 eV, which is one order of magnitude higher of what is experimentally found. Additionally, electrical measurements at different partial pressures of oxygen show that the material has oxygen-ion conductivity, but the activation energy of 0.39 eV suggests other possible mechanisms of electrical conductivity. One of these possibilities is electronic transport, where the activation energy could be due to the band gap. To determine whether electronic conductivity is contributing in the low temperature regime, we performed ab-initio DFT electronic calculations to evaluate the gap, using the modified Becke-Johnson potential. Due to a Ce:4f level found in the gap, which obstructed the convergence of the calculation, we used the LDA + U approach on the Ce atoms, this moves the 4f levels out of the gap. We used the values U = 1, 2 and 3 eV, then extrapolated back to U = 0 to find the location of the Ce:4f state in the gap. The computed value of the activation energy for electronic conductivity is higher than the experimental one, and resembles more the optical gap value found in Ce 1/3 NbO 3 . Based on this result, it can be inferred that the electrical conductivity in Ce 1/3 NbO 3 proceeds via anionic charge carriers in the entire temperature studied range.

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“…This is because ionic conduction in either electrolyte or electrode is crucial to good performance of a fuel cell [6–8], and it is strongly desired to look for new ionic (oxide ion and proton) conductors operating at low and intermediate temperatures [9, 10]. The use of ceria-based materials, especially samaria- or gadolinia-doped ceria (SDC or GDC) as electrolyte or as functional layers between electrolyte and electrode, can significantly lower the operation temperature and increase the performance of solid oxide fuel cells due to their higher oxide ion conductivity (0.02 S cm −1 at 700 °C) [11, 12].…”

Section: Introductionmentioning

confidence: 99%

Novel Nano-composites SDC–LiNaSO4 as Functional Layer for ITSOFC

Tong

Yin

et al. 2015

Nano-Micro Lett.

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As an ionic conductive functional layer of intermediate temperature solid oxide fuel cells (ITSOFC), samarium-doped ceria (SDC)–LiNaSO4 nano-composites were synthesized by a sol–gel method and their properties were investigated. It was found that the content of LiNaSO4 strongly affected the crystal phase, defect concentration, and conductivity of the composites. When the content of LiNaSO4 was 20 wt%, the highest conductivity of the composite was found to be, respectively, 0.22, 0.26, and 0.35 S cm−1 at temperatures of 550, 600, and 700 °C, which are much higher than those of SDC. The peak power density of the single cell using this composite as an interlayer was improved to, respectively, 0.23, 0.39, and 0.88 W cm−2 at 500, 600, and 700 °C comparing with that of the SDC-based cell. Further, the SDC–LiNaSO4(20 wt%)-based cell also displayed better thermal stability according to the performance measurements at 560 °C for 50 h. These results reveal that SDC–LiNaSO4 composite may be a potential good candidate as interlayer for ITSOFC due to its high ionic conductivity and thermal stability.

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Structure and Properties of Novel Cobalt-Free Oxides Nd_xSr_1–xFe_0.8Cu_0.2O_3−δ (0.3 ≤ x ≤ 0.7) as Cathodes of Intermediate Temperature Solid Oxide Fuel Cells

Cited by 105 publications

References 72 publications

Unveiling Lithium Roles in Cobalt‐Free Cathodes for Efficient Oxygen Reduction Reaction below 600 °C

Unveiling Lithium Roles in Cobalt‐Free Cathodes for Efficient Oxygen Reduction Reaction below 600 °C

On the mechanism of electrical conductivity in Ce 1/3 NbO 3

Novel Nano-composites SDC–LiNaSO4 as Functional Layer for ITSOFC

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