Nitrogen-doped carbon nanofibers with effectively encapsulated GeO2 nanocrystals for highly reversible lithium storage
Germanium dioxide is a promising high-capacity anode material for lithium-ion batteries, but it usually exhibits poor cycling stability due to its large volume change during the lithiation/delithiation process. In this paper, homogeneous dispersive GeO2 nanocrystals encapsulated by nitrogen-doped carbon nanofibers (GeO2-CNFs) were prepared by a facile electrospinning technology. The GeO2-CNF anode material exhibited remarkable capability at a high rate and excellent cycling stability (1031 mA h g-1 at 100 mA g-1 after 200 cycles). The good electrochemical performance could be attributed to the fact that ultra-uniform CNFs act as a blocking layer and a buffer layer to effectively hold GeO2 nanocrystals and facilitate the formation of a stable solid electrolyte interphase during Li+ intake/removal. The strategy is a simple and effective method which may be extended to other high-capacity anode materials with a large volume change and low electrical conductivity.