Design of Active Sites on Nickel in the Anode of Intermediate‐Temperature Solid Oxide Fuel Cells using Trace Amount of Platinum Oxides

Abstract

In recent years, the lowering of the operation temperature of solid oxide fuel cells (SOFCs) has attracted much attention owing to the trade‐off between the best performance and the life span of SOFCs. For this challenge, new active sites on the Ni surfaces in a Nickel–Yttria‐Stabilized Zirconia (Ni‐YSZ) cermet anode of SOFCs have been created by deposition of trace amounts of platinum oxide (PtOx) followed by an activation step of the anode at 1073 K in a hydrogen flow. The internal resistance (IR) free value (185 mA cm−2 at 0.8 V) observed for the single cell with an anode sputtered with a trace amount of PtOx (Pt content in anode: from 9 to 91 ppm) at 973 K is conspicuously higher than that of a similar single cell with a nonsputtered cermet anode (85 mA cm−2) at 0.8 V and 1073 K. Transmission electron microscopy microanalysis shows that the defect structure is formed on a partially oxidized Ni surface by active Pt species. Also, surface atomistic simulation on NiO (111) predicts the formation of Frenkel defect clusters with Pt cations, which partially cover the Ni surface. The formation of Frenkel defect clusters on the partially oxidized Ni surface (i.e., creation of new active sites for formation of water molecules) promotes the anode reaction, resulting in improvements in the anode performance of SOFC single cells at 973 K. Design of the aforementioned new active sites on Ni through sputtering of trace amounts of PtOx provides a great opportunity for “radical innovation” in the design of intermediate‐temperature SOFCs.

Integrated Surface Modulation of Ultrahigh Ni Cathode Materials for Improved Battery Performance

“…The most stable (104) surface of the layered structure LiNiO 2 (LNO) was chosen to study the interaction between solvent/anion and cathode materials while the exposed (111) surface with O termination was selected for LNZO as such configuration has the fewest unsaturated sites and the lowest surface energy. [ 51,52 ] The calculated results were shown in Figure 5g, where both adsorption energies of EC and PF 6 − of delithiated LNO are much lower than those of O‐terminated LNZO, indicating a strong interaction. It is therefore reasonable to expect that surface of delithiated LNO is more prone to bond with electrolyte molecules.…”

Design of Active Site at Heterointerface between Brownmillerite Type Oxide Promoter and Fluorite Cubic ZrO2 in Anode of Intermediate Temperature SOFCs

“…The TPBs activated by the precious metal loaded SDC promoter show higher promotion effect and lower overpotential on the anode at 800 °C. Most recently, trace amount of Pt (approximately 9 ppm) conspicuously improved the anode performance of SOFC at 700 °C by formation of unique defect interface structure as active site on partially oxidized Ni surface …”