A new “full fluorosulfonyl” (FFS) electrolyte is developed for highly reversible 4 V class lithium-metal batteries (LMBs).

Diels–Alder cycloaddition with furans as dienes and subsequent dehydrative aromatization are potentially valuable processes for sustainable conversion of biomass-derived furans to aromatics. We have performed electronic structure calculations to investigate the catalytic activity of HY and of alkali-exchanged Y zeolites in connection with the conversion of 2,5-dimethylfuran and ethylene to p-xylene. We have used two active site settings: an active site cluster model on which we have carried out density functional theory calculations and a mechanically embedded active site cluster model on which we have performed hybrid quantum mechanics/molecular mechanics calculations with the ONIOM scheme. Even though Lewis catalyzed Diels–Alder cycloaddition has received considerable attention over the years, we show that confinement and charge transfer in zeolite catalysts play a significant role in catalysis. Both HY and alkali-Y can catalyze the aromatization of the cycloadduct through dehydration but HY is found to be far more effective. Our analysis shows that the electron withdrawing ability of the cations and the catalytic activity of alkali-Y as Lewis acids are diminished by substrate binding-induced electron density shift from the framework oxygen atoms to the cations. On account of these inductive phenomena, we show that the DMF–ethylene cycloaddition follows a bidirectional instead of normal electron flow mechanism.

Fundamental understanding of the reactivity between electrode and electrolyte is key to design the safety and life of Li-ion batteries. Herein X-ray photoelectron spectroscopy was used to examine the electrode/electrolyte interface (EEI) on carbon-free, binder-free LiCoO 2 powder and thin-film electrodes in LP57 electrolyte as function of potential. Upon charging of LiCoO 2 a marked growth of oxygenated and carbonated species was observed on the surface, consistent with electrolyte oxidation at high potentials. We also demonstrated that LiCoO 2 oxide surface was prone to decompose the salt starting at 4.1 V Li , as evidenced by the increase of LiF and Li x PF y O z species upon charging. By DFT calculations we proposed a correlation between the interface composition and the thermodynamic tendency of the EC solvent for dissociative adsorption on the Li x CoO 2 surface, through the generation of reactive acidic OH groups on the oxide surface, which can have a role in the observed salt decomposition. This is consistent with the evidence of HF and PF 2 O 2 − species at 4.6 V Li observed by solution 19 F-NMR measurements. Finally we compared EEI composition between composite and model electrodes and discussed the changes and mechanisms induced by the electrode composition or the use of electrolyte additives. We showed that the addition of diphenyl carbonate (DPC) in the electrolyte has a strong impact on the formation of solvent and salt decomposition products at the EEI layer.

Understanding and controlling non-covalent interactions associated with solvent molecules and redox-inactive ions provide new opportunities to enhance the reaction entropy changes and reaction kinetics of metal redox centers, which can increase the thermodynamic efficiency of energy conversion and storage devices. Here, we report systematic changes in the redox entropy of one-electron transfer reactions including [Fe(CN)6]3-/4-, [Fe(H2O)6]3+/2+ and [Ag(H2O)4]+/0 induced by the addition of redox inactive ions, where approximately twenty different known structure making/breaking ions were employed. The measured reaction entropy changes of these redox couples were found to increase linearly with higher concentration and greater structural entropy (having greater structure breaking tendency) for inactive ions with opposite charge to the redox centers. The trend could be attributed to the altered solvation shells of oxidized and reduced redox active species due to non-covalent interactions among redox centers, inactive ions and water molecules, which was supported by Raman spectroscopy. Not only were these non-covalent interactions shown to increase reaction entropy, but they were also found to systematically alter the redox kinetics, where increasing redox reaction energy changes associated with the presence of water structure breaking cations were correlated linearly with the greater exchange current density of [Fe(CN)6]3-/4-.