Efficient lithium storage of concave graphitic anode embedded with nanoconfined silicon

Abstract

This study reports the use of engineering nanocarbon film with confined silicon nanoparticles as an anode material for lithium-ion batteries. The unique “concave” graphitic nanostructure, prepared in porous templates with morphology of interconnected arrays, makes nanocarbon electrodes a good lithium-ion intercalation medium and, more importantly, robust nanocontainers to effectively confine high-capacity silicon nanoparticles for lithium-ion storage. Open structures of the concave nanocarbon increase the accessibility of Li ions, and allow Li ions to diffuse active materials. In addition, the highly textured concave pores allow the volume expansion of the silicon nanoparticles to be confined to the nanospace during lithium-ion insertion/extraction. The specific capacity of the nanoconfined silicon/nanocarbon anode reaches up to 2500 mAh/g at 0.5 A/g. After long cycling, the anode materials becomes even more stable, showing the invariant lithium-ion storage capacity as the charge-discharge rate is increased by 10 times from 2–20 A/g. The capacity is retained constantly after 200 charge-discharge cycles.