Superior sodium-ion storage performance of Co3O4@nitrogen-doped carbon: derived from a metal–organic framework

Abstract

Nitrogen-doped carbon coated Co₃O₄ nanoparticles (Co₃O₄@NC) with high Na-ion storage capacity and unprecedented long-life cycling stability are reported in this paper. The Co₃O₄@NC was derived from a metal–organic framework ZIF-67, where the Co ions and organic linkers were, respectively, converted to Co₃O₄ nanoparticle cores and nitrogen-doped carbon shells through a controlled two-step annealing process. The Co₃O₄@NC shows a porous nature with a surface area of 101 m² g⁻¹. When applied as an anode for sodium ion batteries (SIBs), Co₃O₄@NC delivers a high reversible capacity of 506, 317, and 263 mA h g⁻¹ at 100, 400, and 1000 mA g⁻¹, respectively. A capacity degradation of 0.03% per cycle over 1100 cycles was achieved at a high current density of 1000 mA g⁻¹. The outstanding Na-ion storage performance can be ascribed to the nitrogen-doped carbon coating (NC), which facilitates the capacitive reaction, minimizes the volume changes of Co₃O₄, and also enhances the electronic conductivity. This work sheds light on how to develop high-performance metal oxide@NC nanocomposites for SIBs.