Electrochemical Performance and Stress Distribution of Sb/Sb2O3 Nanoparticles as Anode Materials for Sodium-Ion Batteries

We synthesize Sb/Sb2O3 nanoparticles by the oxidation of Sb nanoparticles at 100, 200, and 300 degrees C. The half sodium-ion batteries with Sb/Sb2O3-200 exhibit the optimal performance with a charge capacity of 540 mAh g(-1) after 100 cycles at 0.1 A g(-1), maintaining up to six times more capacity than pure Sb, and superior rate performance with 95.7% retention after cycling at varied current densities. One reason for this is that Sb/Sb2O3-200 is at exactly the optimum ratio of Sb2O3:Sb and the particle size of Sb/Sb2O3 to ensure both high capacity for Na+ and small stress during sodiation/desodiation, which is confirmed by the diffusion-stress coupled results. It indicates that increasing the ratio of Sb2O3:Sb causes a decrease of Mises equivalent stress, radial stress, and tangential stress in the range of 1:1-3.5:1, and an increase in the range of 3.5:1-4:1. These stresses decrease with a particle radius in the range of 30-50 nm and increase with a particle radius in the range of 50-70 nm. Additionally, another reason is related to the formation of cycling-induced coral-like Sb, which can promote Na+ diffusion, relieve cycling-induced volume changes, and provide exceptional Na+ storage.