Potassium-sulfur batteries attract tremendous attention as high-energy and low-cost energy storage system, but achieving high utilization and long-term cycling of sulfur remains challenging. Here we show a strategy of optimizing potassium polysulfides for building high-performance potassium-sulfur batteries. We design the composite of tungsten single atom and tungsten carbide possessing potassium polysulfide migration/conversion bi-functionality by theoretical screening. We create two ligand environments for tungsten in the metal-organic framework, which respectively transmute into tungsten single atom and tungsten carbide nanocrystals during pyrolysis. Tungsten carbide provide catalytic sites for potassium polysulfides conversion, while tungsten single atoms facilitate sulfides migration thereby significantly alleviating the insulating sulfides accumulation and the associated catalytic poisoning. Resultantly, highly efficient potassium-sulfur electrochemistry is achieved under high-rate and long-cycling conditions. The batteries deliver 89.8% sulfur utilization (1504 mAh g⁻¹), superior rate capability (1059 mAh g⁻¹ at 1675 mA g⁻¹) and long lifespan of 200 cycles at 25 °C. These advances enlighten direction for future KSBs development.

Atomically dispersed single atom (SA) and atomic cluster (AC) metallic materials attract tremendous attentions in various fields. Expanding monometallic SA and AC to multimetallic SA/AC composites opens vast scientific and technological potentials yet exponentially increasing the synthesis difficulty. Here, we present a general energy-selective-clustering methodology to build the largest reported library of carbon supported bi-/multi-metallic SA/AC materials. The discrepancy in cohesive energy results into selective metal clustering thereby driving the symbiosis of multimetallic SA or/and AC. The library includes 23 bimetallic SA/AC composites, and expanded compositional space of 17 trimetallic, quinary-metallic, septenary-metallic SA/AC composites. We chose bimetallic M¹_SAM²_AC to demonstrate the electrocatalysis utility. Unique decoupled active sites and inter-site synergy lead to 8/47 mV overpotential at 10 mA cm⁻² for alkaline/acidic hydrogen evolution and over 1000 h durability in water electrolyzer. Moreover, delicate modulations towards composition and configuration yield high-performance catalysts for multiple electrocatalysis systems. Our work broadens the family of atomically dispersed materials from monometallic to multimetallic and provides a platform to explore the complex composition induced unconventional effects.

Main group metals are routinely considered as catalytically inactive. In this work, we for the first time prepared a p-block tin single atom catalyst (Sn _SA –NC) with Sn–N ₄ active site for effectively improving the lithium–sulfur battery performance.

Sodium | |sulfur batteries hold great promise for grid-scale energy storage, yet their performance is hindered by the shuttling and sluggish redox of sulfur species. Herein, we report a strategic design of sulfur hosts modified with coordinatively unsaturated iron single-atom (Fe‒N_x) for sodium | |sulfur batteries. Utilizing theoretical calculations, geometric descriptor γ (l_Na‒S/l_Fe‒N) and electronic descriptor φ (e_g /t_2g) simultaneously correlated with the unsaturation degree of Fe‒N_x site are proposed. A negative correlation between γ and the adsorption strength of sodium polysulfides, along with a positive correlation between φ and the decomposition capability of Na₂S are established. The Fe‒N₁ sites, with the minimum γ and maximum φ values, are identified as the optimal functional species for optimizing polysulfides behaviors. Sodium | |sulfur batteries utilizing Fe‒N₁ /S positive electrodes deliver improved sulfur utilization (81.4% at 167.5 mA g^‒1), sustained rate performance (1003.0 mAh g^‒1 at 1675 mA g^‒1), and stable cycling (83.5% retention over 450 cycles at 3350 mA g^‒1). Moreover, Fe‒N₁/S positive electrodes enable sodium | |sulfur pouch cells to deliver a sulfur utilization of 77.4% (1296.9 mAh g^‒1) at 0.1 A g^‒1. Our work offers a strategy for designing high-activity, fast redox sulfur positive electrodes and validates the practical potential of sodium | |sulfur batteries.