Redox-Pathway Reconstruction in Carbonate Electrolyte to Achieve Durable Na─S Battery

The practical performance of room-temperature sodium–sulfur (RT Na─S) batteries in low-solubility carbonate electrolytes is fundamentally constrained by slow “solid-solid” sulfur conversion, causing incomplete redox reactions and rapid capacity fading. Herein, we propose a catalytic strategy via “confinement-pyrolysis” that restructures this static reaction into a dynamic “solid-liquid-solid” pathway. By employing a hierarchical porous framework with atomically dispersed metal sites, the conversion kinetics of sodium polysulfides (NaPSs) are dramatically accelerated. This reconstruction enables continuous liquid-phase intermediates and circumvents the high diffusion barriers of solid-state reactions, as confirmed by density functional theory (DFT) calculations. By simulating long-term cycling through controlled Na₂S deposition, we employed local dipole moment change (Δμ) tracking to reveal the exceptional electronic structure stability and effective lowering of key energy barriers during long-term cycling. As a result, the Fe-N-C/S cathode exhibits outstanding electrochemical performance, delivering a reversible capacity of 799 mAh g⁻¹ at 1 Ag⁻¹ with a capacity decay rate of 0.075% per cycle, and exhibiting an ultralow capacity decay rate of 0.024% per cycle over 2000 cycles at 2 Ag⁻¹. This work elucidates that redox-pathway reconstruction is a pivotal strategy to overcome the inherent kinetic limitations of the conventional mode in carbonate-based Na─S batteries.