Layer-structured Li1-xNaxNi0.8Co0.15Al0.05O2-δ oxide anode for enhancing ceria electrolyte based solid ceramic fuel cell operating at lower temperatures down to 370 °C

A ceria electrolyte-based solid ceramic fuel cell (SCFC) with a layer-structured Li_1-xNa_xNi_0.8Co_0.15Al_0.05O₂ (LNNCA) anode has been developed. The fuel cell with LNNCA anode achieved a maximum power density of 884 mW cm⁻² at 550 °C, which is about 1.6 times higher than the pristine LNCA anode. Meanwhile, the L_0.8N_0.2NCA anode presents a good low temperature characteristic, and it could still be operable at 370 °C with the power density of 63 mW cm⁻². The anchoring effect of doped Na+ plays a vital role in maintaining the layered structure of LNNCA. It decreases Li⁺/Ni²⁺ intermixing, and inhibits Ni growing on the surface of LNNCA, which enhance the catalytic activity and electrical contact of the anode with the ceria electrolyte. Furthermore, Na-doping enriches oxygen vacancies, and promotes the dissociation of adsorbed hydrogen on the surface of LNNCA anode, and thus improves the hydrogen oxidation reaction activity. On the other hand, the in-situ grown NaOH, which has a low-melting temperature, derived from LNNCA anode, can effectively strengthen the bonding between the anode and the electrolyte at the interface, as well as penetrate into electrolyte and provide extra transport channels for proton and other ions, thus decrease the polarization resistance and enable the SCFC to performance even at 370 °C.