Electrolyte design is critical for enabling next-generation batteries with higher energy densities. Hydrofluoroether (HFE) solvents have drawn a lot of attention as the electrolytes based on HFEs showed great promise to deliver highly desired properties, including high oxidative stability, ionic conductivity, as well as enhanced lithium metal compatibility. However, the structure-dynamics-properties relationships and design principles for high-performance HFE solvents are still poorly understood. Herein, we proposed four novel asymmetric HFE designs by systematically varying polyether and fluorocarbon structural building blocks. By leveraging molecular dynamics (MD) modeling to analyze the solvation structures and predict the properties of the corresponding 1 M lithium bis(fluorosulfonyl)imide (LiTFSI) solutions, we downselected the most promising candidate based on high conductivity, solvation species distribution, and oxidative stability for extensive electrochemical characterizations. The formulated electrolyte demonstrated properties consistent with the predictions from the simulations and showed muchimproved capacity retention as well as Coulombic efficiency compared to the baseline electrolytes when cycled in lithium metal cells. This work exemplifies the construction of candidate electrolytes from building block functional moieties to engineer fundamental solvation structures for desired electrolyte properties and guide the discovery and rational design of new solvent materials.

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We utilized quinone redox chemistry to design a new RM for fast and stable cycling of Li-S batteries. Through rational tuning of the redox potential, stability, and solubility of quinones by molecular engineering, we successfully demonstrated that the quinone redox can facilitate the Li 2 S oxidation and the maintained Li 2 S original morphology. The introduction of AQT as an RM is a simple and effective approach to significantly enhance multiple aspects of sulfur redox chemistry under challenging conditions.

Implementation of lithium (Li)-metal anodes requires developments to solve the heterogeneity and instability issues of naturally formed solid-electrolyte interphase (SEI). The artificial SEI, as an alternative, enables an ideal interface by regulating critical features such as fast ion transport, conformal protection, and parasitic reaction mitigation. Herein, for the first time, we integrate all of these desired properties into a single matrix, the dynamic single-ion-conductive network (DSN), as a multifunctional artificial SEI. The DSN incorporates the tetrahedral Al(OR) 4 À (R = soft fluorinated linker) centers as both dynamic bonding motifs and counter anions, endowing it with flowability and Li + single-ion conductivity. Simultaneously, the fluorinated linkers provide chain mobility and electrolyte-blocking capability. A solution-processed DSN coating was found to simultaneously hinder electrolyte penetration, mitigate side reactions between Li and electrolyte, maintain low interfacial impedance, and allow homogenous Li deposition. With this coating, long cycle life and high Coulombic efficiency are achieved for Li-metal battery in a commercial carbonate electrolyte.

In this study, rhombic dodecahedral gold nanocrystals were used as cores for the generation of Au-Ag core-shell nanocrystals with cubic, truncated cubic, cuboctahedral, truncated octahedral, and octahedral structures. Gold nanocrystals were added to an aqueous mixture of cetyltrimethylammonium chloride (CTAC) surfactant, AgNO3, ascorbic acid, and NaOH to form the core-shell nanocrystals. The nanocrystals are highly uniform in size and shape, and can readily self-assemble into ordered packing structures on substrates. Results from observation of solution color changes and variation in the reaction temperature suggest octahedra are produced at a higher growth rate, while slower growth favors cube formation. The major localized surface plasmon resonance (LSPR) band positions for these nanocrystals are red-shifted compared to those for pristine silver particles with similar dimensions due to the LSPR effect from the gold cores. By increasing the concentrations of reagents, Au-Ag core-shell cubes and octahedra with tunable sizes were obtained. Au-Ag cubes with body diagonals of 130, 144, and 161 nm and octahedra with body diagonals of 113, 126, and 143 nm have been prepared, allowing the investigation of size effect on their optical properties. Au-Ag octahedra with thinner Ag shells (12-16.5 nm) exhibit a blue-shifted major LSPR band relative to the LSPR band at 538 nm for the gold cores. For Au-Ag octahedra and cubes with thicker shells (22.5-37 nm), the major LSPR band is progressively red-shifted from that of the gold cores with increasing shell thickness and particle size. The Au-Ag octahedra show higher catalytic activity than cubes toward reduction of 2-amino-5-nitrophenol by NaBH4 at 30 °C, but both particle shapes display significantly enhanced catalytic efficiency at 40 °C.