Sodium Ion Insertion in Hollow Carbon Nanowires for Battery Applications

TLDR

Na‑ion insertion in carbon is facilitated by the short diffusion paths and 0.37 nm interlayer spacing of hollow carbon nanowires, matching theoretical predictions. Hollow carbon nanowires were fabricated by pyrolyzing a hollow polyaniline nanowire precursor. As anode material, the HCNWs deliver 251 mAh g⁻¹ with 82.2 % capacity retention after 400 cycles at 0.2 C, maintain excellent stability at higher rates, and achieve 149 mAh g⁻¹ at 2 C.

Abstract

Hollow carbon nanowires (HCNWs) were prepared through pyrolyzation of a hollow polyaniline nanowire precursor. The HCNWs used as anode material for Na-ion batteries deliver a high reversible capacity of 251 mAh g(-1) and 82.2% capacity retention over 400 charge-discharge cycles between 1.2 and 0.01 V (vs Na(+)/Na) at a constant current of 50 mA g(-1) (0.2 C). Excellent cycling stability is also observed at an even higher charge-discharge rate. A high reversible capacity of 149 mAh g(-1) also can be obtained at a current rate of 500 mA g(-1) (2C). The good Na-ion insertion property is attributed to the short diffusion distance in the HCNWs and the large interlayer distance (0.37 nm) between the graphitic sheets, which agrees with the interlayered distance predicted by theoretical calculations to enable Na-ion insertion in carbon materials.