Solvent-Solvent Interaction Mediated Lithium-Ion (De)intercalation Chemistry in Propylene Carbonate Based Electrolytes for Lithium-Sulfur Batteries

Reversible lithium-ion (de)intercalation in the carbon-based anodes using ethylene carbonate (EC) based electrolytes has enabled the commercialization of lithium-ion batteries, allowing them to dominate the energy storage markets for hand-held electronic devices and electric vehicles. However, this issue always fails in propylene carbonate (PC) based electrolytes due to the cointercalation of Li+-PC. Herein, we report that a reversible Li+ (de)intercalation could be achieved by tuning the solvent-solvent interaction in a PC-based electrolyte containing a fluoroether. We study the existence of such previously unknown interactions mainly by nuclear magnetic resonance (NMR) spectroscopy, while the analysis reveals positive effects on the solvation structure and desolvation process. We have found that the fluoroether solvents interact with PC via their δ-F and δ+H atoms, respectively, leading to a reduced Li+-PC solvent interaction and effective Li+ desolvation followed by a successful Li+ intercalation at the graphite anodes. We also propose an interfacial model to interpret the varied electrolyte stability by the differences in the kinetic and thermodynamic properties of the Li+-solvent and Li+-solvent-anion complexes. Compared to the conventional strategies of tuning electrolyte concentration and/or adding additives, our discovery provides an opportunity to enhance the compatibility of PC-based electrolytes with the graphite anodes, which will enable the design of high-energy density batteries (e.g., Li-S battery) with better environmental adaptabilities.

Ultrastable Cu2+ Intercalation Chemistry Based on a Niobium Sulfide Nanosheet Cathode for Advanced Aqueous Storage Devices

Exploring stable and durable cathodes for cost-effective reversible aqueous batteries is highly desirable for grid-scale energy storage applications, but significant challenges remain. Herein, we disclosed an ultrastable Cu²⁺ intercalation chemistry in mass-produced exfoliated NbS₂ nanosheets to build ultralong lifespan aqueous batteries with cost advantages. Anisotropic interplanar expansion of NbS₂ lattices balanced dynamic Cu²⁺ incorporation and the highly reversible redox reaction of Nb⁴⁺/Nb^(4-δ)+ couple were illuminated by operando synchrotron X-ray diffraction and energy dispersive X-ray absorption spectroscopy, affording an extraordinary capacity of approximately 317 mAh g^-1 at 1 A g^-1 and a good stability of 92.2% capacity retention after 40000 cycles at 10 A g^-1. Impressively, a budget NbS₂||Fe hybrid ion cell involving an aqueous electrolyte/Fe-metal anode is established and provides a reliable energy supply of 225.4 Wh kg^-1 at 750 W kg^-1, providing insights for building advanced aqueous battery systems for large-scale applications.