Tandem Catalysis Overcomes the Rate‐Determining Sulfur Conversion Cascade in Na─S Batteries

Abstract

ABSTRACT Room‐temperature sodium–sulfur (RT Na─S) batteries offer high theoretical energy density and low cost, yet their practical performance is fundamentally limited by sluggish sulfur redox kinetics, particularly the intertwined kinetic limitations of late‐stage Na 2 S 4 →Na 2 S 2 →Na 2 S conversions. Here, we propose a step‐targeted tandem catalysis strategy that integrates atomically dispersed Fe‐N 4 sites with polar ZrO 2 nanodomains within a conductive carbon host to precisely regulate the rate‐determining sulfur conversion cascade. Density functional theory reveals a step‐specific catalytic sequence, in which Fe‐N 4 preferentially lowers the activation barrier for Na 2 S 4 →Na 2 S 2 conversion, while ZrO 2 thermodynamically drives the subsequent Na 2 S 2 →Na 2 S step. Their electronic coupling creates a continuous activation landscape that accelerates the entire solid‐solid reaction cascade. Experimental kinetic analyses corroborate this mechanism, showing reduced polarization, enhanced surface‐controlled kinetics, and mitigated transport limitations. As a result, the tandem‐catalyzed Na─S cathode delivers an initial capacity of 1408 mAh g −1 , ultralong cycling stability over 10 000 cycles at a high current density of 5 A g −1 , and robust operation at −20°C. This work establishes tandem catalysis as an effective design paradigm for precisely regulating multistep sulfur conversion reactions in Na─S batteries.