SnSe2 nanocrystals coupled with hierarchical porous carbon microspheres for long-life sodium ion battery anode

Tin selenides have been attracting great attention as anode materials for the state-of-the-art rechargeable sodium-ion batteries (SIBs) due to their high theoretical capacity and low cost. However, they deliver unsatisfactory performance in practice, owing to their intrinsically low conductivity, sluggish kinetics and volume expansion during the charge-discharge process. Herein, we demonstrate the synthesis of SnSe2 nanocrystals coupled with hierarchical porous carbon (SnSe2 NCs/C) microspheres for boosting SIBs in terms of capacity, rate ability and durability. The unique structure of SnSe2 NCs/C possesses several advantages, including inhibiting the agglomeration of SnSe2 nanoparticles, relieving the volume expansion, accelerating the diffusion kinetics of electrons/ions, enhancing the contact area between the electrode and electrolyte and improving the structural stability of the composite. As a result, the as-obtained SnSe2 NCs/C microspheres show a high reversible capacity (565 mA h g−1 after 100 cycles at 100 mA g−1), excellent rate capability, and long cycling life stability (363 mA h g−1 at 1 A g−1 after 1000 cycles), which represent the best performances among the reported SIBs based on SnSe2-based anode materials.