Interfacial Chemistry Regulation via a Skin-Grafting Strategy Enables High-Performance Lithium-Metal Batteries

The lithium (Li) metal anode suffers severe interfacial instability from its high reactivity toward liquid electrolytes, especially carbonate-based electrolytes, resulting in poor electrochemical performance of batteries that use 4 V high-capacity cathodes. We report a new skin-grafting strategy that stabilizes the Li metal–liquid electrolyte interface by coating the Li metal surface with poly­((<i>N</i>-2,2-dimethyl-1,3-dioxolane-4-methyl)-5-norbornene-<i>exo</i>-2,3-dicarboximide), a chemically and electrochemically active polymer layer. This layer, composed of cyclic ether groups with a stiff polycyclic main chain, serves as a grafted polymer skin on the Li metal anode not only to incorporate ether-based polymeric components into the solid-electrolyte interphase (SEI) but also to accommodate Li deposition/dissolution under the skin in a dendrite/moss-free manner. Consequently, a Li-metal battery employing a Li metal anode with the grafted skin paired with LiNi_0.5Co_0.2Mn_0.3O₂ cathode has a 90.0% capacity retention after 400 charge/discharge cycles and a capacity of 1.2 mAh/cm² in a carbonate-based electrolyte. This proof-of-concept study provides a new direction for regulating the interfacial chemistry of Li metal anodes and for enabling high-performance Li-metal batteries

Electrolysis of Gaseous CO₂ to CO in a Flow Cell with a Bipolar Membrane

The conversion of CO₂ to CO is demonstrated in an electrolyzer flow cell containing a bipolar membrane at current densities of 200 mA/cm² with a Faradaic efficiency of 50%. Electrolysis was carried out by delivering gaseous CO₂ at the cathode with a silver catalyst integrated in a carbon-based gas diffusion layer. Nonprecious nickel foam in a strongly alkaline electrolyte (1 M NaOH) was used to mediate the anode reaction. While a configuration where the anode and cathode were separated by only a bipolar membrane was found to be unfavorable for robust CO₂ reduction, a modified configuration with a solid-supported aqueous layer inserted between the silver-based catalyst layer and the bipolar membrane enhanced the cathode selectivity for CO₂ reduction to CO. We report higher current densities (200 mA/cm²) than previously reported for gas-phase CO₂ to CO electrolysis and demonstrate the dependence of long-term stability on adequate hydration of the CO₂ inlet stream

Controlled Exfoliation of MoS₂ Crystals into Trilayer Nanosheets

The controlled exfoliation of transition metal dichalcogenides (TMDs) into pristine single- or few-layer nanosheets remains a significant barrier to fundamental studies and device applications of TMDs. Here we report a novel strategy for exfoliating crystalline MoS₂ into suspensions of nanosheets with retention of the semiconducting 2H phase. The controlled reaction of MoS₂ with substoichiometric amounts <i>n</i>-butyl­lithium results in intercalation of the edges of the crystals, which are then readily exfoliated in a 45 vol % ethanol–water solution. Surprisingly, the resulting colloidal suspension of nanosheets was found (by electron microscopy and atomic force microscopy) to consist mostly of trilayers. The efficiency of exfoliation of the pre-intercalated sample is increased by at least 1 order of magnitude relative to the starting MoS₂ microcrystals, with a mass yield of the dispersed nanosheets of 11–15%

Fast and Efficient Preparation of Exfoliated 2H MoS₂ Nanosheets by Sonication-Assisted Lithium Intercalation and Infrared Laser-Induced 1T to 2H Phase Reversion

Exfoliated 2H molybdenum disulfide (MoS₂) has unique properties and potential applications in a wide range of fields, but corresponding studies have been hampered by the lack of effective routes to it in bulk quantities. This study presents a rapid and efficient route to obtain exfoliated 2H MoS₂, which combines fast sonication-assisted lithium intercalation and infrared (IR) laser-induced phase reversion. We found that the complete lithium intercalation of MoS₂ with butyllithium could be effected within 1.5 h with the aid of sonication. The 2H to 1T phase transition that occurs during the lithium intercalation could be also reversed by IR laser irradiation with a DVD optical drive