CoS 2 Nanoparticles Embedded in Two‐Dimensional Sheet‐Shaped N‐Doped Carbon for Sodium Storage

Na-ion batteries (NIBs) have attracted more and more attention due to the plentiful resources of sodium, excellent ion storage capacity and superior cycle life. However, the implementation of NIBs has been limited by the shortage of electrode materials with outstanding comprehensive properties. Among the discovered anode materials, transition metal sulfides (TMSs) have been widely considered as one of the most competitive and promising ones due to their high theoretical specific capacity. Herein, CoS2 nanoparticles embedded in nitrogen-doped carbon nanosheets (CoS2/NC) were designed and synthesized by using Co-based Metal-organic frame-work (Co-MOF) as precursor of metal sulfurs, followed by a simple combined carbonization-sulfurization process. The CoS2/NC compo-sites were evaluated as binder-free anode materials for NIBs, delivering a high reversible gravimetric capability of 332 mA h g(-1) after 60 cycles as well as great rate capability of 326.6 mA h g(-1) at 2000 mA g(-1). The improvement of electrochemical behavior is attributed to the synergistic interaction between CoS2 nanoparticles with high electro-chemical activity and the sheet-shaped N-doped carbon with high conductivity. This work provides a greatly attractive strategy for energy conversion and storage.