Electrode Properties of the Ruddlesden–Popper Series, La_n+1Ni_nO_3n+1 (n=1, 2, and 3), as Intermediate‐Temperature Solid Oxide Fuel Cells

Abstract

The Ruddlesden–Popper phases, Lan+1NinO3n+1 (n=1, 2, and 3), were synthesized by a solid‐state reaction for use as cathodes in an intermediate‐temperature (500°–700°C) solid oxide fuel cell. The samples crystallized into an orthorhombic layered perovskite structure. The overall electrical conductivity increased with the increase of n in the intermediate temperature range. Single test‐cells, which consisted of samarium‐oxide‐doped ceria (SDC; Sm0.2Ce0.8Ox) as an electrolyte, Ni–SDC cermet (Ni–SDC) as an anode, and Lan+1NinO3n+1 as a cathode, were fabricated for measurements of cell performance at 500°–700°C. Current interruption measurements revealed that both the ohmic and overpotential losses at 700°C decreased with the increase of n. La4Ni3O10 was found to exhibit the best cathode characteristics in the Lan+1NinO3n+1 series. Maximum test‐cell power densities with La4Ni3O10 (n=3) were 10.2, 36.5, and 88.2 mW/cm2 at 500°, 600°, and 700°C, respectively.

Scale-Down and Sr-Doping Effects on La4Ni3O10-δ–YSZ Nanocomposite Cathodes for IT-SOFCs

“…An electrolytesupported single cell (LSNO-YSZ/YSZ/Ce-Pd-YSZ) based on a ∼120 μm YSZ electrolyte was fabricated to measure the electrochemical performance of the LNO-YSZ cathode. The maximum power density of the LNO nanocomposite was 0.385 W cm −2 at 700 • C. In comparison with the power density of bulk LNO, 4,19,31,32 the value of LNO here is reasonable considering that a thick YSZ electrolyte (∼120 μm) was used in this study without any buffer layer. The electrolyte is responsible for the higher ohmic resistance and consequently lower power density.…”

“…19,29,31 Thus, it can be concluded that the LNO nanocomposite has lower ASR with faster oxygen diffusion kinetics in the cathode than the bulk LNO. Additionally, Figure 5 shows that the cathode ASR values of LSNO4 and LSNO8 cathodes are 0.195, 0.274 cm 2 , respectively, at 700…”

Functionally graded composite La 2 NiO 4+δ and La 4 Ni 3 O 10−δ solid oxide fuel cell cathodes

“…Total conductivity in these R-P phases is known to increase with n [7,24], and it has been shown that this is maintained in porous electrode layers [9], so it is consistent that an outer L4N3 layer lowers the polarisation resistance. Current collectors are known to improve electrode performance and have been utilised with these La-Ni R-P materials before [16,17,25].…”

Advances in Cathode Materials for Solid Oxide Fuel Cells: Complex Oxides without Alkaline Earth Metal Elements

“…[ 349 ] More intriguingly, they may also show an improved ORR activity than La 2 NiO 4 . [348][349][350][351] Oxygen hypo-stoichiometry, instead of hyperstoichiometry, was typically observed in these high-order Ruddlesden-Popper phases. [ 261,354 ] In a recent study, Woolley et al precisely determined the valence state of Ni in La 2 NiO 4+δ and La 4 Ni 3 O 10-δ by X-ray absorption spectroscopy of the near-edge region of the Ni K-edge at room temperature and 650 °C.…”

“…[ 348 ] The electrochemical performance of these higher order Ruddlesden-Popper phases has been investigated. [ 261,348,349,351 ] From symmetrical cell tests, the La 4 Ni 3 O 9.78 coated LSGM electrolyte pellet yielded the lowest ASR of ≈1 Ω cm 2 at 800 °C with an activation energy of E a = 1.36 eV, followed by La 3 Ni 2 O 6.95 and La 2 NiO 4.15 with E a = 1.27 and 1.24 eV, respectively. [ 348 ] The peak power densities of a cell with a La 4 Ni 3 O 10 electrode reached 10.2, 36.5, and 88.2 mW cm −2 at 500, 600, and 700 °C, respectively.…”