Synthesis of Hollow Carbon Microspheres with Tunable Shell Numbers for High-Performance Anode Material in Lithium-Ion Batteries.

In this paper, hollow carbon microspheres (HCMs) with tunable shell numbers were controllably synthesized by the combination of facile hydrothermal method and etching treatment. The microstructure, morphology and electrochemical performance of HCMs were investigated by X-ray photoelectron, spectra SEM and TEM measurements, and galvanostatic charge-discharge tests. The size of HCMs was uniform and increased with increasing the number of inner carbon shells. Compared to the single-layer carbon microspheres and double-layer carbon microspheres, threelayer HCMs (TLCs) with diameters of 310-360 nm exhibited the highest reversible capacity presenting original discharge and charge capacity of 626.04 and 575.68 mAh·g-1 at 0.1 C. Moreover, the capacitance retention reached to 360 mAh ·g-1 and charge-discharge efficiency was still over 97% after 100 cycles. The superior properties of TLCs can be mainly attributed to their unique three-layer hollow structure which can significantly enhance the pore volume and specific surface area, and thus provides more Li-ions reaction sites and larger contact area between electrodes. Furthermore, the design strategy of HCMs is expected to provide a novel guidance for the design of multi-layer carbon structure with improved electrochemical properties.