Designing Urchin-Like S@SiO₂ with Regulated Pores Toward Ultra-Fast Room Temperature Sodium-Sulfur Battery

Captured by high theoretical capacity and low-cost, Sodium-Sulfur (Na-S) batteries have been deemed as promising energy-storage systems. However, their electrochemical properties, containing both cycling and rate properties, still suffer from the notorious "shuttle effect" of polysulfide. Herein, through the effective regulation of pore sizes, a series of S@SiO2 cathode materials are obtained. Benefitting from the abundant pore channels of SiO2 particles, the sulfur loading is as high as 76.3%. Importantly, a suitable pore size can lead to adequate reaction and rapid diffusion behaviors, resulting in excellent electrochemical performances. Specifically, at 2.0 A g(-1), the initial capacity of the as-optimized sample can be up to 1370.6 mAh g(-1). Surprisingly, even after 1050 cycles, it could achieve a high reversible capacity of 1280.8 mAh g(-1) with an attenuation rate of 0.089%. At 5.0 A g(-1), after 500 cycles, the capacity can still remain approximate to 1132.6 mAh g(-1) (capacity retention rate, 97.5%). Given this, the work is anticipated to offer an effective strategy for advanced electrodes for Na-S batteries.