Dual Functions of Potassium Antimony(III)-Tartrate in Tuning Antimony/Carbon Composites for Long-Life Na-Ion Batteries

Antimony holds a high-specific capacity as a promising anode material for Na-ion batteries (SIBs) and much research is focused on solving the poor cycling stability issue associated with its large volume expansion during alloying/dealloying processes. Here, self-thermal-reduction method is successfully applied to prepare antimony/carbon rods (Sb/C rods) utilizing potassium antimony(III)-tartrate (C8H10O15Sb2K2) as a dual source of carbon matrix and metallic antimony. According to theory calculations and experiment results, the formation process is explicitly explored as follows: C8H10O15Sb2K2 -> Sb2O3/C -> Sb2O3/Sb/C -> Sb/C rods. Notably, organic ligands in C8H10O15Sb2K2 can be gradually turned into amorphous carbon with simultaneous reduction of Sb3+ to metal Sb. Moreover, potassium chloride acts as an activator and a template during the course of carbonization, and synchronous reduction is introduced. Consequently, an antimony/carbon electrode material denoted as Sb-O-C/C is formed, exhibiting a unique dual-carbon-modified structure and extensive Sb-O-C bridge bonds that give rise to outstanding cycling performance and rate capacity. Specifically, the capacity is maintained at 404 mA h g(-1) with 89% retention after 700 cycles at 500 mA g(-1). The low-cost, self-thermal-reduction method and excellent electrode performances of electrode material make it attractive for large-scale energy storage systems.