Optimizing potassium polysulfides for high performance potassium-sulfur batteries

Abstract

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.

Electrolyte Intermolecular Interaction Mediated Nonflammable Potassium-Ion Sulfur Batteries

“…This result is consistent with those previously reported, which are different from the “solid–liquid–solid” reaction mechanism observed in conventional K–S batteries using the sulfur-based cathode . The reason for the slow capacity decay in the following cycles could be ascribed to the quality of the SPAN cathode, whose purity is hard to control at an extremely high degree in the synthesis process . We believe the performance could be further improved by optimizing the SPAN cathode and potassium ion battery fabrication processes.…”

“…58 The reason for the slow capacity decay in the following cycles could be ascribed to the quality of the SPAN cathode, whose purity is hard to control at an extremely high degree in the synthesis process. 59 We believe the performance could be further improved by optimizing the SPAN cathode and potassium ion battery fabrication processes. More importantly, by employing the SPAN cathode instead of the potassium metal counter electrode (i.e., graphite || K half-cell), the KC 8 || SPAN full cell can work reversibly, reconfirming the capability of our custom-designed electrolyte that can enable a reversible K + (de)intercalation within the graphite electrode.…”

Insights into the Optimization of Catalytic Active Sites in Lithium–Sulfur Batteries

“…Wan et al pioneered the introduction of SCMs into LSBs, sparking a fervent wave of research in this field (Figure c) . Various types of SCMs have been developed, including iron, cobalt, nickel, molybdenum, manganese, vanadium, tungsten, niobium, platinum, and others (Figure b). , However, the overloading of single atoms (5%) results in aggregation, which limits the overall number of active sites. This necessitates the development of efficient manufacturing processes to synthesize single atoms with higher loads.…”