Hierarchical carbon nanocages as high-rate anodes for Li- and Na-ion batteries

Novel hierarchical carbon nanocages (hCNCs) are proposed as high-rate anodes for Li- and Na-ion batteries. The unique structure of the porous network for hCNCs greatly favors electrolyte penetration, ion diffusion, electron conduction, and structural stability, resulting in high rate capability and excellent cyclability. For lithium storage, the corresponding electrode stores a steady reversible capacity of 970 mAh center dot g(-1) at a rate of 0.1 A center dot g(-1) after 10 cycles, and stabilizes at 229 mAh center dot g(-1) after 10,000 cycles at a high rate of 25 A center dot g(-1) (33 s for full-charging) while delivering a large specific power of and specific energy of . For sodium storage, the hCNC reaches a high discharge capacity of similar to 50 mAh center dot g(-1) even at a high rate of 10 A center dot g(-1).