Ultrasonic spray infiltration is demonstrated by surface tailoring of LSCF/GDC cathodes by generating high dispersion and epitaxial deposition of Sm0.5Sr0.5CoO3 catalyst nanolayer, which promotes high and stable performance outcomes of the SOFCs.

Cr poisoning of cathode materials is one of the main degradation issues hampering the operation of solid oxide fuel cells (SOFCs). To overcome this shortcoming, LaNi 0.6 Fe 0.4 O 3−δ (LNF) has been developed as an alternative cathode material owing to its superior chemical stability in Cr environments. In this study, we develop a hybrid electrochemical deposition technique to fabricate a nanostructured LNF− gadolinium-doped ceria (GDC) (n-LNF−GDC) cathode with enhanced active reaction sites for the oxygen reduction reaction. For this purpose, Fe and Ni cations are co-deposited onto an electrically conductive carbon nanotube-modified GDC backbone by electroplating, whereas La cations are successively deposited through a chemically assisted electrodeposition method. The proposed method involves a low-temperature (900 °C) calcination step of electrodeposited cations, which avoids the need of fabricating a GDC diffusion barrier layer which is otherwise needed to avoid the formation of insulating phases (e.g., La 2 Zr 2 O 7 ) when fabricating by conventional high-temperature (≥1000 °C) sintering. Scanning electron microscopy images reveal a unique nanofibrous structure of n-LNF−GDC, which is believed to play an instrumental role in enhancing the electrochemical characteristics by increasing the active triple-phase boundaries. An anode-supported SOFC with the n-LNF−GDC cathode showed the superior performance of 0.984 W cm −2 at an intermediate temperature of 750 °C as compared to the power densities of 0.495 and 0.874 W cm −2 produced by LNF−GDC and state-of-the-art La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3−δ (LSCF)−GDC composite cathodes fabricated by conventional sintering. A short-term accelerated Cr-poisoning durability test indicated good electrochemical stability of n-LNF−GDC, whereas LSCF exhibited severe degradation. The electrochemically engineered nanostructured n-LNF−GDC can serve as an effective cathode for SOFCs to achieve high performance and long-term durability.

A dense Ce0.9Gd0.1O2−d (GDC) interlayer is an essential component of the SOFCs to inhibit interfacial elemental diffusion between zirconia‐based electrolytes (eg YSZ) and cathodes. However, the characteristic high sintering temperature of GDC (>1400°C) makes it challenging to fabricate an effective highly dense interlayer owing to the formation of more resistive (Zr,Ce)O2 interfacial solid solutions with YSZ at those temperatures. To fabricate a useful GDC interlayer, we studied the influence of transition metal (TM) (Co, Cu, Fe, Mn, & Zn) doping on the sintering and electrochemical properties of GDC. Dilatometry data showed dramatic drops in the necking and final sintering temperatures for the TM‐doped GDCs, improving the densification of the GDC in the order of Fe > Co > Mn > Cu > Zn. However, the electrochemical impedance data showed that among various transition metal dopants, Mn doping resulted in the best electrochemical properties. Anode supported SOFCs with Mn‐doped, nano, and commercial‐micron GDC interlayers were compared with regard to their performance and stability levels. Although all of the SOFCs showed stable performance, the SOFC with the Mn‐doped GDC interlayer showed the highest power density of 1.14 W cm−2 at 750°C. Hence, Mn‐doped GDC is suggested for application as an effective diffusion barrier layer in SOFCs.

Over several decades, solid-state electrodes in which reversible intercalation (insertion) and deintercalation (extraction) of cationic guest atoms occur along with accompanying electron flow without any change of their crystal structure, have attracted great interest in fundamental and practical perspectives for improving the performance of rechargeable batteries. This chapter provides comprehensive reviews of principle and recent advances especially in thermodynamic and kinetic approaches to lithium intercalation into, and deintercalation from, transition metals oxides and carbonaceous materials. Thermodynamic properties such as chemical potential, entropy and enthalpy of lithium intercalation/deintercalation are first discussed, based on a lattice gas model with various approximations. Lithium intercalation/deintercalation involving an order-disorder transition or a two-phase coexistence caused by strong interaction of lithium ions in solid-state electrodes is explained, based on the lattice gas model and with the help of computational methods. Second, the kinetics of lithium intercalation/ deintercalation is treated in detail on the basis of a cell-impedance-controlled model. Anomalous features of potentiostatic current transients obtained experimentally from transitional metal oxide and carbonaceous electrodes, which are hardly explained under a diffusion control model, are readily analyzed by the cell-impedancecontrolled lithium transport concept, with the aid of computational methods. IntroductionWhen cationic guest atoms such as lithium, hydrogen, and sodium reversibly enter or leave the host oxide crystal, along with an accompanying electron flow but without any change in crystal structure, the reaction is referred to as intercalation/ deintercalation as follows [1,2]::1Þ Solid State Electrochemistry I: Fundamentals, Materials and their Applications. Edited by Vladislav V. Kharton