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

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.