Hierarchical design of carbon nanofibers wrapped antimony selenide nanorods with heteroatom-doped carbon quantum dots as efficient anode material of high-performance sodium-ion batteries

Abstract

Researchers have focused on sodium-ion batteries (SIBs) due to low precursor costs and abundant reserves. However, low efficiency of anode materials hinders SIB commercialization, mainly due to large ionic radius and slow kinetics of Na+. Metal selenides such as Sb2Se3 have regarded as promising anode materials of SIBs due to high theoretical capacities. Despite this, the practical application has been limited by the poor rate capability, conductivity, and stability. In this study, one-dimensional Sb2Se3 nanorods and nitrogen-doped carbon quantum dots (N-CQDs) combined with carbon nanofibers (CNFs) have been developed as an effective anode material of SIBs. The uniform distribution of N-CQDs in the Sb2Se3 coated CNFs (Sb2Se3/CNFs) anode results in the highest reversible capacity of 647.9 mAhg−1 at 0.05 Ag-1. Moreover, the Sb2Se3 and N-CQDs coated CNFs (Sb2Se3@N-CQDs/CNFs) anode presents a good rate performance and retains a high reversible capacity of 444.7 mAhg−1 at a high current density of 0.4 Ag-1. Additionally, the Sb2Se3@N-CQDs/CNFs anode demonstrates excellent stability, retaining 78.8% of the initial capacity after 100 cycles. The improved electrochemical performance is attributed to low volume expansion and good conductivity due to carbon coating and addition of N-CQDs. Galvanostatic intermittent titration technique is also used to examine Na+ diffusion coefficients.