Constructing highly active surface-nanostructured core/bi-shell La1.2Sr0.8Ni0.5Mn0.5O4+δ cathode for protonic ceramic fuel cells

Abstract

Development of highly-active electrodes is essential yet challenging for the designs of low-temperature protonic ceramic fuel cells (LT-PCFCs). Herein, a core/bi-shell surface-nanostructure on base of K2NiF4-type La1.2Sr0.8Ni0.5Mn0.5O4+δ (LSNM) is developed. With the occurence of dopant segregation during atom arrangement in powder calcination process, the core/bi-shell is formed, accompanied by the formations of B-site deficient K2NiF4 phase and perovskite separately existing in two shell-regions, which could promote oxygen reduction and proton migration, thus extending the cathode reaction. The DFT simulation also provides further evidence of easily proton transfer for facilely rotating and jumping. This unique LSNM cathode attains an impressive power approaching 1.1 W cm−2 at 650 °C, outperforming other Ln2NiO4-based cathodes in the literature. On balance, the predominant cell performance coupled with good durability suggests that the core/bi-shell LSNM is a preferential alternative for LT-PCFCs. This work provides a new strategy to design highly-active electrode materials via decorating surface structure, which would be beneficial to the related electrocatalytic fields.