A general strategy to construct yolk-shelled metal oxides inside carbon nanocages for high-stable lithium-ion battery anodes

Metal oxides (MOs) are attractive anode materials of Li-ion batteries for the large theoretical capacity, low cost and high density, but suffer from the poor cycling stability owing to the low conductivity, large volume variation, active component loss and instable solid electrolyte interface (SEI) during cycling. Herein, we develop a simple and general strategy to construct the yolk-shelled metal oxides inside 3D hierarchical carbon nanocages (hCNC). The obtained yolk-shelled MO@hCNC provides sufficient interior void to buffers the large volume variation, forms the stable SEI film, and greatly reduces the loss of active components during lithiation/delithiation, meanwhile ensures the fast electron transfer and ions/electrolyte transportation. Both SnO₂@hCNC and Fe₃O₄@hCNC exhibit superior cycling stability and reversible capacity to the most corresponding SnO₂- and Fe₃O₄-based anode materials reported to date. The simple and general approach to the yolk-shelled MO@hCNC is significant for exploring the high-performance energy-storage materials for Li-ion batteries or even beyond.