Constructing CoO/Co3S4 Heterostructures Embedded in N-doped Carbon Frameworks for High-Performance Sodium-Ion Batteries

Heterostructures are attractive for advanced energy storage devices due to their rapid charge transfer kinetics, which is of benefit to the rate performance. The rational and facile construction of heterostructures with satisfactory electrochemical performance, however, is still a great challenge. Herein, ultrafine hetero-CoO/Co3S4 nanoparticles embedded in N-doped carbon frameworks (CoO/Co3S4@N-C) are successfully obtained by employing metal-organic frameworks as precursors. As anodes for sodium ion batteries, the CoO/Co3S4@N-C electrodes exhibit high specific capacity (1029.5 mA h g(-1) at 100 mA g(-1)) and excellent rate capability (428.0 mA h g(-1) at 5 A g(-1)), which may be attributed to their enhanced electric conductivity, facilitated Na+ transport, and intrinsic structural stability. Density functional theoretical calculations further confirm that the constructed heterostructures induce electric fields and promote fast reaction kinetics in Na+ transport. This work provides a feasible approach to construct metal oxide/sulfide heterostructures toward high-performance metal-ion batteries.