Ultrasmall Sn Nanodots Dispersed in Cross-Linked N-Doped Carbon Cages for High-Performance Lithium Storage

Abstract

Sn based materials are the promising anodes in Li-ion batteries for the advantages of high theoretical capacity (994 mAh g-1 for LIBs), high conductivity and low cost. However, the drastic volume change during charging and discharging process results in poor cycling stability. Dispersing nano-sized Sn particles in carbon matrix is an effective way to mitigate the volume change, but the thick carbon matrix may retard ion diffusion. Consider this, we designed nano-Sn/N-doped carbon microcages composites (Sn/NMCs) with Sn nanodots uniformly dispersed inside the N-doped carbon microcages through a simple spray drying process, followed by thermal treatment. The interconnected N-doped carbon skeleton enhances the electronic conductivity, meanwhile the internal channels supply fast paths for Li+ transmission. Taking the advantages of ultrasmall Sn and soft carbon matrix, the Sn/NMCs exhibit excellent electrochemical performance as Li-ion battery anode. It delivers an initial charging capacity of 780 mAh g-1 at 200 mA g-1, and maintains 472 mAh g-1 after 500 cycle.; 323 mAh g-1 is still maintained even at a high current density of 10 A g-1. Moreover, this Sn/NMCs is accessible to scale up and the modification strategy can be extended to other electrode materials. Figure 1 TEM image of Sn/NMCs and the schematic diagram of Li+ and electron transportation processes in Sn/NMCs Acknowledgments This work is supported by the National Natural Science Foundation of China (Grant No. 51371186), the “Strategic Priority Research Program” of the Chinese Project Academy of Science (Grant No.XDA09010201), Ningbo 3315 International Team of Advanced Energy Storage Materials, Zhejiang Province Key Science and Technology Innovation Team (2013TD16). Figure 1