Simultaneous ferrocenyl and pentafluorophenyl substituted Ni(II) and Zn(II) porphyrins successfully exhibited sufficient electrochemical properties, capable of being used as practical electrode materials for secondary sodium batteries. Fc−ZnPor electrodes furnished superior rapid sodium ion storage properties and stable cycling performances compared to Fc−H₂Por and Fc−NiPor electrodes.

Abstract

This study investigates the potential use of ferrocenyl-substituted porphyrins as organic electrode materials for sodium secondary batteries. Expressly, 5,15-di(ferrocenyl)-10,20-di(pentafluorophenyl)porphyrins (free base, Fc−H₂Por), along with its zinc (Zn[II] complex, Fc−ZnPor) and nickel (Ni[II] complex, Fc−NiPor) derivatives were synthesized and employed as the electrode materials. The charge-discharge processes disclosed that the ferrocenyl-substituted porphyrin compound performs electrochemical processes poorly without chelating metals. In contrast, when the ferrocenyl-substituted porphyrins were metalated with Ni(II) and Zn(II), they exhibited dual ionic charge-discharge capabilities, indicating their stable electrochemical properties. In particular, long-term cycle tests emphasized the superior stability and high Coulombic efficiency of Fc−ZnPor electrodes. Computational calculations provided conclusive evidence of variances in aromatic stabilization energy based on the metal center, significantly influencing the chemical stability and electrochemical performance. These findings can deliver valuable insight for further development and optimizations in energy storage applications.