SeC Bonding Promoting Fast and Durable Na+ Storage in Yolk–Shell SnSe2@SeC

Tin‐based compounds have received much attention as anode materials for lithium/sodium ion batteries owing to their high theoretical capacity. However, the huge volume change usually leads to the pulverization of electrode, giving rise to a poor cycle performance, which have severely hampered their practical application. Herein, highly durable yolk–shell SnSe2 nanospheres (SnSe2@SeC) are prepared by a multistep templating method, with an in situ gas‐phase selenization of the SnO2@C hollow nanospheres. During this process, Se can be doped into the carbon shell with a tunable amount and form SeC bonds. Density functional theory calculation results reveal that the SeC bonding can enhance the charge transfer properties as well as the binding interaction between the SnSe2 core and the carbon shell, favoring an improved rate performance and a superior cyclability. As expected, the sample delivers reversible capacities of 441 and 406 mAh g−1 after 2000 cycles at 2 and 5 A g−1, respectively, as the anode material for a sodium‐ion battery. Such performances are significantly better than the control sample without the SeC bonding and also other metal selenide‐based anodes, evidently showing the advantage of Se doping in the carbon shell. Yolk–shell SnSe2@C nanospheres with SeC bonds in the carbon shell are synthesized by selenization of the SnO2@C precursor. Density functional theory calculation results reveal that the SeC bonding can enhance the charge transfer properties and the binding energy between the SnSe2 core and the carbon shell, leading to greatly improved high‐rate performance and cycling stability for a sodium‐ion battery.