Boosting sodium-ion battery performance using an antimony nanoparticle self-embedded in a 3D nitrogen-doped carbon framework anode

Sb-based alloying-type materials are considered as a promising anode material for sodium-ion batteries (SIBs) owing to their advantages, such as a suitable potential and high theoretical capacity. However, these materials undergo a significant volume change during cycling, leading to degraded electrochemical performance. In this study, rational Sb@NC composites featuring Sb nanoparticles self-embedded in a 3D porous N-doped carbon framework were synthesised using a NaCl sacrificial template. This novel synthesis method can be used to fabricate Sb@NC composites with a unique structure, which confers them with good conductivity, mitigates volume expansion, and prevents the Sb nanoparticles from agglomerating during cycling. As a SIB anode, the optimised Sb@NC M10 composite, which was synthesised with 68.25 wt% of Sb and 10 g of NaCl sacrificial template, exhibited a high reversible capacity of 622.5 mAh g-1 at 0.1 C after 100 cycles and 572.1 mAh g-1 at 1 C after 500 cycles. Moreover, a full cell featuring Sb@NC M10 anode and Na3V2(PO4)2O2F cathode showed remarkable reversible capacity of 512.7 mAh g-1 even after 100 cycles at a charge-discharge rate of 0.1 C and an energy density of 281 Wh kg-1. Furthermore, Density functional theory (DFT) calculations revealed that doping N into the carbon framework of the composites improved the electronic properties and enhanced the Sb/Na binding on the N-doped carbon layer of the composite carbon framework. Accordingly, the Sb@NC composites maintained their structural integrity during cycling. Based on its remarkable electrochemical performance, the Sb@NC M10 anode material is promising for practical applications in commercial SIBs.