Binary Atomic Sites Enable a Confined Bidirectional Tandem Electrocatalytic Sulfur Conversion for Low-Temperature All-Solid-State Na-S Batteries.

The broader implementation of current all-solid-state Na-S batteries is still plagued by high operation temperature and inefficient sulfur utilization. And the uncontrollable sulfur speciation pathway along with the sluggish polysulfide redox kinetics further compromise the theoretical potentials of Na-S chemistry. Herein, we report a confined bidirectional tandem electrocatalysis effect to tune polysulfide electrochemistry in a novel low-temperature (80 °C) all-solid-state Na-S battery that utilizes Na 3 Zr 2 Si 2 PO 12 ceramic membrane as a platform. The bifunctional hollow sulfur matrix consisting binary atomically dispersed MnN 4 and CoN 4 hotspots was fabricated using a sacrificial template process. Upon discharge, CoN 4 sites activate sulfur species and catalyze long-chain to short-chain polysulfides reduction, while MnN 4 centers substantially accelerate the low-kinetic Na 2 S 4 to Na 2 S directly conversion, manipulating the uniform deposition of electroactive Na 2 S and avoiding the formation of irreversible products (e.g., Na 2 S 2 ). The intrinsic synergy of two catalytic centers benefits the Na 2 S decomposition and minimizes its activation barrier during battery recharging and then efficiently mitigate the cathodic passivation. As a result, the stable cycling of all-solid-state Na-S cell delivers an attractive reversible capacity of 1060 mAh g -1 with a high CE of 98.5 % and a high energy of 1008 Wh kg cathode -1 , comparable to the liquid electrolyte cells.