Tellurium doped sulfurized polyacrylonitrile nanoflower for high-energy-density, long-lifespan sodium-sulfur batteries.

Sodium-sulfur (Na−S) batteries are promising energy storage devices for large-scale applications due to their high-energy-density and abundant material reserve. However, the practical implementation of room temperature (RT) Na−S batteries faces challenges, including low-energy-density and limited lifespan, particularly attributed to the properties of sulfurized polyacrylonitrile (SPAN). In this study, we address these challenges by introducing tellurium doping into SPAN nanoflowers, enhancing their performance for Na−S batteries. The resulting material exhibits high sulfur loading as well as superior electron and ion transport properties, leading to enhanced redox kinetics and improved battery performance. The tellurium-doped SPAN nanoflower electrode delivers an exceptional composite capacity of 700 mAh g⁻¹ at 0.1 C and demonstrates stable cycling over 2400 cycles with minimal capacity fade (0.01 % average fading rate). Even under challenging conditions (24.0 mg cm⁻², E/S=5 mg μL S ⁻¹, N/P=2.1), the Na−S battery achieves a high areal capacity of 16.1 mAh cm⁻², resulting in an impressive energy density of 340.9 Wh kg^–1 based on cathode and anode. This work presents a promising approach to designing high-energy-density, long-lifespan RT Na−S batteries, with potential applications for other metal-sulfur battery systems. [Display omitted] • The synergy of Te-doping and nanoflower enables SPAN-based cathode with superior kinetics and high capacity. • Sulfur cathode exhibits ultrahigh specific capacities and remarkable long-lifespan in Na−S batteries. • Na-S cell delivers an ultrahigh areal capacity of 16.1 mAh cm⁻² and a calculated energy density of 340.9 Wh kg⁻¹ [ABSTRACT FROM AUTHOR]