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·g^-1 at a rate of 0.1 A·g^-1 after 10 cycles, and stabilizes at 229 mAh·g^-1 after 10, 000 cycles at a high rate of 25 A·g^-1 (33 s for full-charging) while delivering a large specific power of 37 kW∙kg_electrode^–1 and specific energy of 339 Wh∙k_gelectrode^–1. For sodium storage, the hCNC reaches a high discharge capacity of ~50 mAh·g^-1 even at a high rate of 10 A·g^-1.