RESUMEN
Rechargeable metal-sulfur batteries are considered promising candidates for energy storage due to their high energy density along with high natural abundance and low cost of raw materials. However, they could not yet be practically implemented due to several key challenges: (i) poor conductivity of sulfur and the discharge product metal sulfide, causing sluggish redox kinetics, (ii) polysulfide shuttling, and (iii) parasitic side reactions between the electrolyte and the metal anode. To overcome these obstacles, numerous strategies have been explored, including modifications to the cathode, anode, electrolyte, and binder. In this review, the fundamental principles and challenges of metal-sulfur batteries are first discussed. Second, the latest research on metal-sulfur batteries is presented and discussed, covering their material design, synthesis methods, and electrochemical performances. Third, emerging advanced characterization techniques that reveal the working mechanisms of metal-sulfur batteries are highlighted. Finally, the possible future research directions for the practical applications of metal-sulfur batteries are discussed. This comprehensive review aims to provide experimental strategies and theoretical guidance for designing and understanding the intricacies of metal-sulfur batteries; thus, it can illuminate promising pathways for progressing high-energy-density metal-sulfur battery systems.
RESUMEN
Sodium-sulfur (Na-S) batteries with durable Na-metal stability, shuttle-free cyclability, and long lifespan are promising to large-scale energy storages. However, meeting these stringent requirements poses huge challenges with the existing electrolytes. Herein, a localized saturated electrolyte (LSE) is proposed with 2-methyltetrahydrofuran (MeTHF) as an inner sheath solvent, which represents a new category of electrolyte for Na-S system. Unlike the traditional high concentration electrolytes, the LSE is realized with a low salt-to-solvent ratio and low diluent-to-solvent ratio, which pushes the limit of localized high concentration electrolyte (LHCE). The appropriate molecular structure and solvation ability of MeTHF regulate a saturated inner sheath, which features a reinforced coordination of Na+ to anions, enlarged Na+ -solvent distance, and weakened anion-diluent interaction. Such electrolyte configuration is found to be the key to build a sustainable interphase and a quasi-solid-solid sulfur redox process, making a dendrite-inhibited and shuttle-free Na-S battery possible. With this electrolyte, pouch cells with decent cycling performance under rather demanding conditions are demonstrated.
RESUMEN
High-voltage spinel LiNi0.5Mn1.5O4 (LNMO) is a promising next-generation cathode material due to its structural stability, high operation voltage, and low cost. However, the cycle life of LNMO cells is compromised by detrimental electrode-electrolyte reactions, chemical crossover, and rapid anode degradation. Here, we demonstrate that the cycling stability of LNMO can be effectively enhanced by a high-energy laser treatment. Advanced characterizations unveil that the laser treatment induces partial decomposition of the polyvinylidene fluoride binder and formation of a surface LiF phase, which mitigates electrode-electrolyte side reactions and reduces the generation of dissolved transition-metal ions and acidic crossover species. As a result, the solid electrolyte interphase of the graphite counter electrode is thin and is composed of fewer electrolyte decomposition products. This work demonstrates the potential of laser treatment in tuning the surface chemistry of cathode materials for lithium-ion batteries.
RESUMEN
Nanomodification and amorphization are vital for improving the hydrogenation properties of magnesium (Mg)-based alloys. However, comparisons of their positive effects have been rarely presented because their usual fabrication process of annealing is hard to control. In this study, after tuning the composition fluctuation range, self-assembled well-ordered multilayer Mg0.7Gd0.3 films with an excessive amount of nanosized crystals were fabricated by deviating substrates to the edge of the sample stage, while relatively low crystallinity was gained at the center of the sample stage with a small composition fluctuation. It was demonstrated that the hydrogen diffusion rate in the sample deposited at the center with excessive amorphous regions was higher than that of the film fabricated at the edge with excessive nanocrystals regions. Besides, optical conversion ranges were monitored before and after the hydrogen absorption process. Films with large composition fluctuation possessed a high optical reflectance conversion range because the interference effects occurring inside improved their initial reflectance. However, films with small composition fluctuation inside gained a large transmittance conversion range due to their small nanostructured region.
