A New Strategy for Achieving a High Performance Anode for Lithium Ion Batteries-Encapsulating Germanium Nanoparticles in Carbon Nanoboxes

摘要

A novel strategy to improve the electrochemical performance of a germanium anode is proposed via encapsulating germanium nanoparticles in carbon nanoboxes by carbon coating the precursor, germanium dioxide cubes, and then subjecting them to a reduction treatment. The complete and robust carbon boxes are shown to not only provide extra void space for the expansion of germanium nanoparticles after lithium insertion but also offer a large reactive area and reduced distance for the lithium diffusion. Furthermore, the thus-obtained composite, composed of densely stacked carbon nanoboxes encapsulating germanium nanoparticles (germanium@carbon cubes (Ge@CC)), exhibits a high tap density and improved electronic conductivity. Compared to carbon-coated germanium bulks, the Ge@CC material shows excellent electrochemical properties in terms of both rate capability and cycling stability, due to the unique cubic core-shell structure and the effective carbon coating, so that the Ge@CC electrode delivers approximate to 497 mA h g(-1) at a current rate of 30 C and shows excellent cycling stability of 1065.2 mA h g(-1) at 0.5 C for over 500 cycles.