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Highlights: [•] Different water dosages can produce silver nanoparticles with controllable shapes. [•] Granule-like silver nanoparticles possess relatively high absorption. [•] Plate-like particles have relatively high transmittance. [•] Silver nanoparticles with different shapes show selective SERS enhancement. [ABSTRACT FROM AUTHOR]

Rather than preventing the dissolution and diffusion of polysulfides, promoting polysulfide conversion through improved polysulfide redox is another promising strategy to suppress the dissolution of polysulfides and enhance the cycle life of sulfur cathodes. We demonstrated that VO 2 -rGO not only facilities liquid-involving polysulfide redox (Li 2 S 8 →Li 2 S 6 →Li 2 S 4), but also promotes the effective decompositions of lithium sulfide (Li 2 S). As evidenced by the visual experiments and DFT calculation, VO 2 -rGO has strong affinity for polysulfides species. With sulfur loading of 2.15 mg cm−2 and sulfur content of 76 wt%, the reversible capacity retained at 896 mAh g−1 after 200 cycles. • Highly porous structure is generated after VO 2 nanorods are embedded in rGO. • VO 2 can efficiently promote the phase transformation of polysulfide. • This electrode can last for 200 cycles with reversible capacity of 896 mAh g−1. [ABSTRACT FROM AUTHOR]

The sodium-sulfur (Na/S) batteries have caused widespread concern owing to the advantages of low cost and high energy density, these advantages make them promising in the large-scale energy storage system. But the research progress in this field is still at the beginning stage and confronts with tough challenges, for example, the low sulfur conductivity and polysulfide shuttle effect. Considering Na/S battery is a complicated system whose reaction mechanism between sulfur and sodium is different from the operating temperatures, positive electrode hosts and electrolytes, thus a comprehensive understanding about the electrochemistry of the Na/S batteries that operating in high-temperature, intermediate-temperature and room-temperature is necessary. In addition, the critical factors (positive electrodes, electrolytes, separators) associated with the development of high energy density and high performance Na/S battery, it also need to be analysed for the successful application in the near future. In this review, the working methods of high-temperature Na/S (HT-Na/S) battery, intermediate-temperature Na/S (IT-Na/S) battery and room-temperature Na/S (RT-Na/S) battery will be compared, and also focus on the latest progress of positive electrodes, electrolytes and separators in Na/S batteries. Finally, we provide an outlook on the state of the art for the production of more efficient and reliable Na/S batteries with rational technique. Image 1 • Analyse the reaction mechanisms, merits and drawbacks of three different types of Na-S batteries. • Summarize the latest progress of positive electrode materials and discuss the underlying problems of Na-S battery. • Analyse the basic function of separators in Na-S battery and further discuss the importance of separators. • Contrast Na-S batteries with other secondary batteries from the perspective of commercial application. • Analyse the future research direction of each type of factors and provide a vision of efforts for Na-S batteries. [ABSTRACT FROM AUTHOR]