Metal-organic framework derived in-situ nitrogen-doped carbon-encapsulated CuS nanoparticles as high-rate and long-life anode for sodium ion batteries

Transition metal sulfides (TMSs) have been considered as the most promising candidates for anode materials of sodium-ion batteries (SIBs) due to their high theoretical specific capacity. However, large volume expansion caused by conversion reaction during sodiation-desodiation processes generally leads to poor structural stability. Herein, metal-organic framework (MOF)-derived in-situ nitrogen-doped partially graphitized carbon-encapsulated CuS nanoparticles ([email protected]) has been successfully prepared via a two-step process of carbonization and sulfidation. The preparation strategy using Cu-MOF as precursor realizes in-situ encapsulation of CuS into nitrogen-doped carbon matrix, simultaneously endowing the [email protected] with high conductivity and rigid structure protection. As a result, the [email protected] shows an excellent electrochemical properties as an anode of SIBs: delivering the satisfying rate capability of 259.4 mAh g−1 at 5 A g−1 and exhibiting the high reversible capacity of 300.2 mAh g−1 after 1200 cycles at 5 A g−1 with an ultra-low capacity decay of 0.0035% per cycle. This study proposes an effective strategy to develop novel anodes with excellent cycling and rate properties for SIBs by encapsulating active nanoparticles into carbon matrix.