Confined tandem catalytic quasi-solid sulfur reversible conversion for all-solid-state Na–S batteries†
Abstract
Controlling the complex, multiphase sulfur/polysulfide redox process is a fundamental pathway to alleviate the cathodic passivation and unlock the high energy potentials of all-solid-state Na–S electrochemistry. Herein, by employing a confined tandem electrocatalytic approach, we successfully tune the polysulfide speciation pathway to enable energetic, low-temperature (80 °C) Na–S systems based on dense Na3Zr2Si2PO12 ceramic membranes. Our design features york–shell structured MnHCF/PPy@MnO2 coaxial nanotubes endowed with a localized and confined environment. These components synergistically catalyze the conversion of encapsulated sulfur/sulfide, with MnO2 effectively directing long-chain polysulfide transition and MnHCF nanoclusters catalyzing low-kinetic Na2S4 to Na2S direct and reversible conversion. This facilitates continuous, fully controllable quasi-solid sulfur conversion, significantly enhancing battery performance. Operando investigations show that, without the mediation of these bi-catalytic centers, the electrodeposited Na2S2/Na2S exhibits a much higher activation energy upon recharging, leading to the accumulation of inactive polysulfide species and exacerbated cathodic passivation. Consequently, our approach enables a low N/P ratio all-solid-state Na–S cell with a high reversible capacity of 1111 mA h gS−1 and an energy output of 880 W h kgcathode−1.