Transition metal oxide (MO_x) offers great potential as anode for lithium ion batteries (LIBs) due to the high theoretical capacity compared with that of commercial graphite. However, several limitations, such as large volume variation during repeated cycling, slow kinetics and low electrical conductivity, have severely limited the practical performance in application. Here, we report a rational design of hollow metal oxide/carbon core-shell fibers (MO_x/C, M= Sn, Ge) and the synthesis of the material via facile co-axial electrospinning process (Figure 1a). The unique hollow core-shell structure of MO_x/C with MO_x nanoparticles encapsulated into hollow carbon shells can provide a buffer layer to suppress the fracture of MOx nanoparticles caused by repeated volume changes, good conductivity and short diffusion paths for Li ions as well as stable solid electrolyte interphase (SEI) layer. Meanwhile, sufficient space between MOx nanoparticles and the carbon shell is contributed to accommodate the volume expansion of MOx during cycling process (Figure 1b–1c). As the anodes for LIBs, the as-prepared SnO₂/C and GeOx/C electrodes exhibit excellent lithium storage performance, showing high reversible specific capacity of 833 mAh g⁻¹ after 500 cycles at 600 mA g⁻¹ and 875 mA h g⁻¹ after 400 cycles at 160 mA g⁻¹, respectively. The structural design in this paper can provide a novel strategy for the research of high-performance anode materials for LIBs.

References:
[1] Dan Zhou, Wei-Li Song, Li-Zhen Fan*. ACS Appl. Mater. Interfaces, 2015, 7, 21472−21478
[2] Meng Li, Dan Zhou, Wei-Li Song, Xiaogang Li, Li-Zhen Fan*. J. Mater. Chem. A, 2015, 3, 19907−19912.