Self-Standing Carbon Nanofiber and SnO₂ Nanorod Composite as a High-Capacity and High-Rate-Capability Anode for Lithium-Ion Batteries

We fabricated a composite of self-standing carbon nanofibers (CNFs) and nanorod-like SnO₂ (CNF@SnO₂) for use as an anode for a lithium-ion battery (LIB), via electrospinning and hydrothermal synthesis methods using naturally abundant, environmentally friendly, and cost-effective materials. The composite electrode is flexible and can be directly used as an LIB anode without a metal collector. The nanorod-like structure of SnO₂ accommodates the dramatic volume expansion intrinsic to SnO₂ during charge-discharge cycles, increases the specific surface area, and decreases the charge-Transfer resistance. CNF@SnO₂ exhibits a discharge capacity of 800 mAh g^-1 under 0.5 A g^-1 during the second cycle, 2.8 times higher than the capacity of the CNF-only electrode (285 mAh g^-1 under the same condition). This high capacity is realized by the high reversibility of the conversion reaction of SnO₂, arising from its well-organized nanostructure. Further, CNF@SnO₂ shows excellent rate capability; it maintains 49% of its second discharge capacity at current densities reaching 4.0 A g^-1. This high rate capability is attributed to the high degree of CNF graphitization. Overall, CNF@SnO₂ exhibits a high capacity, good rate capability, and excellent potential as a candidate LIB anode material.