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

Nitrogen-doped carbon coated Co 3 O 4 nanoparticles (Co 3 O 4 @NC) with high Na-ion storage capacity and unprecedented long-life cycling stability are reported in this paper. The Co 3 O 4 @NC was derived from a metal – organic framework ZIF-67, where the Co ions and organic linkers were, respectively, converted to Co 3 O 4 nanoparticle cores and nitrogen-doped carbon shells through a controlled two-step annealing process. The Co 3 O 4 @NC shows a porous nature with a surface area of 101 m 2 g 1 . When applied as an anode for sodium ion batteries (SIBs), Co 3 O 4 @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 Co 3 O 4 , and also enhances the electronic conductivity. This work sheds light on how to develop high-performance metal oxide@NC nanocomposites for SIBs