Novel multi-layered 1-D nanostructure exhibiting the theoretical capacity of silicon for a super-enhaced lithium-ion battery

Abstract: This work reports on robust tri-layer-compartmentalized carbon core/silicon medium/carbon shell nanofibers as negative electrode material for Li-ion batteries. The feasibility of the tri-layered co-axial electrospinning system has been examined via simply designed numerical modeling as well as wire-in-tube structured carbon nanofiber preparation. Then, the carbon core/silicon medium/carbon shell tri-layered nanofibers have been successfully fabricated by adopting the tri-layered co-axial electrospinning and subsequent thermal treatment. The robust tri-layered structure and lack of the chemical reaction between Si and C components have been characterized. The super-enhanced electrochemical performances are finally demonstrated via Galvanostatic charge/discharge test. The reversible capacity of the tri-layered nanofiber (1210.7 mAh g-1) at the current rate of 50 mA g-1 is increased compared to that of the core/shell structured nanofiber. Especially, the realization of the theoretical specific capacity of Li15Si4 phase of Si nanoparticles (3627.3 mAh g-1) clearly demonstrates the strength of the core carbon layer. The fact that the specific capacity retention of the tri-layered nanofibers (more than 820 mAh g-1) at the current rate of 12,000 mA g-1 is much higher than that of the core/shell structured nanofibers (less than 200 mAh g-1) also implies the excellence of the tri-layered structure.