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

Abstract

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 Na3Zr2Si2PO12 ceramic membrane as a platform. The bifunctional hollow sulfur matrix consisting binary atomically dispersed MnN4 and CoN4 hotspots was fabricated using a sacrificial template process. Upon discharge, CoN4 sites activate sulfur species and catalyze long‐chain to short‐chain polysulfides reduction, while MnN4 centers substantially accelerate the low‐kinetic Na2S4 to Na2S directly conversion, manipulating the uniform deposition of electroactive Na2S and avoiding the formation of irreversible products (e.g., Na2S2). The intrinsic synergy of two catalytic centers benefits the Na2S 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 kgcathode−1, comparable to the liquid electrolyte cells.

Preparation of high-quality lithium sulfide by reducing lithium sulfate with hydrogen: a green and cost-effective method

“…It can not only be used to synthesize a sulfide solid electrolyte but also serves as a lithium–sulfur cathode. 9–11 When exposed to air, Li 2 S will quickly react with H 2 O to produce the rotten egg-like pungent smell of H 2 S gas, and this will itself also be oxidized by O 2 to deposit sulfur (S). 12 The entire process of synthesizing Li 2 S in the laboratory should be conducted in the glove box where the concentration of H 2 O and O 2 is less than 1 ppm.…”

Confined tandem catalytic quasi-solid sulfur reversible conversion for all-solid-state Na–S batteries

“…7–10 In this context, the incorporation of inorganic solid electrolytes provides a viable strategy to redress the polysulfide shuttle phenomenon. 11–13 However, the issues of the uncontrollable sulfur speciation pathway remain unresolved. To this end, the development of a quasi-solid state sulfur reversible conversion that dissolves only a small fraction of intermediates provides an ideal platform for tuning the redox chemistry of sulfur species within a solid cell (Fig.…”

“…1,10,12,16,17 However, studies on understanding the sulfur redox in low-temperature (<100 °C) batteries using solid electrolytes are still in their infancy. 13,18–20 Seminal works showed that the soft PEO-NaFSI gel binder could efficiently overcome the interfacial challenges and facilitate a continuous 3D ionic transport path in solid-state metal–sulfur batteries, thus providing a deeper understanding of the redox chemistry during dynamic battery discharge/charge. 21–24 Designing a matrix with a desirable architecture ( e.g.…”

“…9,28,29 Nonetheless, a recently established electrocatalysis and/or co-catalysis strategy did not provide a “root” solution to manipulate the multistep sulfur conversion behavior in practical Na–S cells. 13,30–32 The key to achieving tunable sulfur conversion within the hierarchically porous matrix lies in efficiently embedding multi-catalytic centers while designing novel confined interspaces with high reactivity.…”