Structural Engineering of Multishelled Hollow Carbon Nanostructures for High-Performance Na-Ion Battery Anode

Hard carbon has long been considered the leading candidate for anode materials of Na-ion batteries. Intensive research efforts have been carried out in the search of suitable carbon structure for an improved storage capability. Herein, an anode based on multishelled hollow carbon nanospheres, which are able to deliver an outstanding electrochemical performance with an extraordinary reversible capacity of 360 mAh g(-1) at 30 mA g(-1), is designed. An interesting dependence of the electrochemical properties on the multishelled structural features is identified: with an increase in the shell number of the model carbon materials, the sloping capacity in the charge/discharge curve remains almost unchanged while the plateau capacity continuously increases, suggesting an adsorption-filling Na-storage mechanism for the multishelled hollow hard carbon materials. The findings not only provide new perspective in the structural design of high-performance anode materials, but also shed light on the complicated mechanism behind Na-storage by hard carbon.