Porphyrin–graphene oxide frameworks for long life sodium ion batteries

Abstract

Herein, we demonstrate that a porphyrin interspersed graphene-oxide framework with a d-spacing of ∼7.67 Å can significantly enhance the cycling stability of graphene-based anodes in sodium-ion batteries. These robust electrodes can deliver a reversible capacity of ∼200 mA h g⁻¹ at a current density of 100 mA g⁻¹ in the 20^th cycle with negligible capacity fading over 700 cycles. In addition to the superior rate tolerance, the specific capacity was stable even after a resting time of one month. The excellent performance may be nested in the larger interlayer spacing, and rich nitrogen content along with the defect sites available for sodium interaction. Experimental studies and density functional theory calculations presented in this work give insights into the structure–property relationship of porphyrin–graphene oxide frameworks and their electrochemical performance.