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Yuan, Yating

Publications and source records attributed to Yuan, Yating.

7 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Lattice engineering of high-entropy olivine-type lithium metal phosphate as high-voltage cathodes

Engineering of high-entropy cathode materials for lithium-ion batteries has been actively pursued owing to the outstanding conductivity of high-entropy materials benefited from the maximum entropy and unique antisite disordering structure. Olivine lithium metal phosphates such as LiMnPO 4 and LiNiPO 4 feature high working voltages but low capacities due to their insulation nature. Here in this work, the synthesis of the high-entropy lithium metal phosphate materials (HELMPs) is realized by combining mechanochemistry with a calcination method. By regulating lattice of HELMPs, the high-entropy Li(Mn 0.35 Fe 0.35 Co0.1Mg 0.1 Ca 0.1 )PO 4 reveals three typical high-voltage plateaus in charge–discharge curves corresponding to the redox of Fe, Mn, and Co in the voltage range of 2.0–4.9 V vs Li + /Li, and a much higher initial capacity than LiMnPO 4 (104 vs 15 mAh g -1 ).

25 ENERGY STORAGE↗
DOE OSTI2023

Facile Room-Temperature Electrodeposition of Rare Earth Metals in a Fluorine-Free Task-Specific Electrolyte

Electrochemical deposition of rare earth metals at room temperature has attracted increasing interest due to its advantage in energy efficiency over traditional hydrometallurgical and pyrometallurgical processes. Recent progress has been made with fluorinated electrolyte systems; however, the formation of an electrode-passivating fluoride layer by electrolyte decomposition is often overlooked. Such a passivation layer causes significant and rapid decay of the deposition current and significantly hinders practical application. To address this issue, we demonstrate a fluorine (F)-free task-specific electrolyte utilizing the borohydride anion for the efficient electrodeposition of rare earth metals. By eliminating the passivation effect, the deposition process exhibits a stable current and accumulates a thick neodymium deposit on the electrode. Raman spectroscopy of the electrolyte reveals a synergetic effect between rare earth borohydride and lithium borohydride which promotes the dissociation of both borohydride salts, resulting in significantly increased ionic conductivity and electrochemical performance. Cyclic voltammetry and in-depth X-ray photoelectron spectroscopy of the deposits suggest that the electrodeposition of rare earth metals could undergo a Li-mediated reduction process. Finally, quantitative analysis of the deposits reveals that the overall concentration of the rare earth elements reaches 75% which contains 40–48% metallic phase.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Mechanochemically Assisted Synthesis of High-Entropy Layer-Structured Dittmarite Analogues

High-entropy solid-solution materials, especially layered ones incorporating five or more near-equimolar components into single-phase crystal structures, may spark functional synergism toward the electrochemistry area because of their unique antisite disordering structures and the synergistic effect of multiple active sites. Herein, high-entropy dittmarite analogues (HEDAs) were synthesized via a mechanochemistry-assisted hydrothermal method. Furthermore, the as-prepared HEDAs have single dittmarite phases with five homogeneously distributed metal elements, exhibiting enhanced activities in oxygen evolution catalysis compared to the single metal counterparts.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Benzene Ring Knitting Achieved by Ambient-Temperature Dehalogenation via Mechanochemical Ullmann-Type Reductive Coupling

The current approaches capable of affording conjugated porous networks (CPNs) still rely on solution-based coupling reactions promoted by noble metal complexes or Lewis acids, on-surface polymerization conducted in ultrahigh-vacuum environment at very high temperatures (>200 °C), or mechanochemical Scholl-type reactions limited to electron-rich substrates. To develop simple and scalable approaches capable of making CPNs under neat and ambient conditions, herein, a novel and complementary method to the current oxidative Scholl coupling processes is demonstrated to afford CPNs via direct aromatic ring knitting promoted by mechanochemical Ullmann-type reactions. The key to this strategy lies in the dehalogenation of aromatic halides in the presence of Mg involving the formation of Grignard reagent intermediates. Products (Ph-CPN-1) obtained via direct C-C bond formation between 1,2,4,5-tetrabromobenzene (TBB) monomer feature high surface areas together with mesoporous architecture. The versatility of this approach is confirmed by the successful construction of various CPNs via knitting of the corresponding aromatic rings (e.g., pyrene and triphenylene), and even highly crystalline graphite product was obtained. The CPNs exhibit good electrochemical performance as the anode material in lithium-ion batteries (LIBs). Overall, this approach expands the frontiers of CPN synthesis and provides new opportunities to their scalable applications.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Perovskite Oxide–Halide Solid Solutions: A Platform for Electrocatalysts

The successful integration or hybridization of perovskite oxides with their halide cousins would enable the formation of both multi-anionic and multi-cationic solid solutions with unique metal-ion sites and synergistic properties that could potentially surpass the performance of classic perovskites. However, such solid solutions had not been produced previously owing to their distinct formation energies and different synthesis conditions. Solid solutions combining perovskite oxides with fluorides were produced in this study by mechanochemical synthesis. The obtained perovskite oxide–halide solid solutions had highly mixed elements and valences, uniform element distributions, and single-phase crystalline structures. In this work, the solid solution with an optimized combination of oxides and fluorides exhibited enhanced catalytic performance in the oxygen evolution reaction.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗