Degradation Mechanism of Dimethyl Carbonate (DMC) Dissociation on the LiCoO₂ Cathode Surface: A First-Principles Study

The degradation mechanism of dimethyl carbonate electrolyte dissociation on the (010) surfaces of LiCoO₂ and delithiated Li_1/3CoO₂ were investigated by periodic density functional theory. The high-throughput Madelung matrix calculation was employed to screen possible Li_1/3CoO₂ supercells for models of the charged state at 4.5 V. The result shows that the Li_1/3CoO₂(010) surface presents much stronger attraction toward dimethyl carbonate molecule with the adsorption energy of −1.98 eV than the LiCoO₂(010) surface does. The C–H bond scission is the most possible dissociation mechanism of dimethyl carbonate on both surfaces, whereas the C–O bond scission of carboxyl is unlikely to occur. The energy barrier for the C–H bond scission is slightly lower on Li_1/3CoO₂(010) surface. The kinetic analysis further shows that the reaction rate of the C–H bond scission is much higher than that of the C–O bond scission of methoxyl by a factor of about 10³ on both surfaces in the temperature range of 283–333 K, indicating that the C–H bond scission is the exclusive dimethyl carbonate dissociation mechanism on the cycled LiCoO₂(010) surface. This study provides the basis to understand and develop novel cathodes or electrolytes for improving the cathode–electrolyte interface

Kinetic Insights into a Surface-Designed Au₁@Pt₈/CeO₂ Catalyst in the Base-Free Oxidation of Biomass-Derived Tetrahydrofuran-2,5-dimethanol

Oxidizing alcohols to carboxylic acids presents the challenge of preserving reactivity and selectivity and minimizing alkali additives, necessitating precision construction of the catalytic surface to guide selective oxidation behavior. In this study, we designed core–shell structured catalysts with controllably tunable surface components for highly efficient oxidation of biomass-derived tetrahydrofuran-2,5-dimethanol (THFDM) to tetrahydrofuran-2,5-dicarboxylic acid under base-free conditions, offering a potential alternative to petro-based 1,4-cyclohexanedicarboxylic acid. The optimized Au1@Pt8/CeO2 catalyst breaks the constraints arising from intertwined electronic and geometric structures, achieving a desirable balance between activity and selectivity. More importantly, kinetic analysis and Langmuir–Hinshelwood (L–H) modeling demonstrate enhanced adsorption of both THFDM and oxygen, subsequently altering the rate-determining step

Effect of LiFSI Concentrations To Form Thickness- and Modulus-Controlled SEI Layers on Lithium Metal Anodes

Improving the cyclic stability of lithium metal anodes is of particular importance for developing high-energy-density batteries. In this work, a remarkable finding shows that the control of lithium bis­(fluorosulfonyl)­imide (LiFSI) concentrations in electrolytes significantly alters the thickness and modulus of the related SEI layers, leading to varied cycling performances of Li metal anodes. In an electrolyte containing 2 M LiFSI, an SEI layer of ∼70 nm that is obviously thicker than those obtained in other concentrations is observed through <i>in situ</i> atomic force microscopy (AFM). In addition to the decomposition of FSI^– anions that generates rigid lithium fluoride (LiF) as an SEI component, the modulus of this thick SEI layer with a high LiF content could be significantly strengthened to 10.7 GPa. Such a huge variation in SEI modulus, much higher than the threshold value of Li dendrite penetration, provides excellent performances of Li metal anodes with Coulombic efficiency higher than 99%. Our approach demonstrates that the FSI^– anions with appropriate concentration can significantly alter the SEI quality, establishing a meaningful guideline for designing electrolyte formulation for stable lithium metal batteries