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Regulating single-crystal LiNiO2 size and surface coating toward a high-capacity cathode for lithium-ion batteries
(American Chemical Society, 2023-05-03) Lee, DH; Avdeev, M; Kim, DI; Shin, WH; Hong, J; Kim, MK
Single crystals recently received a great deal of attention because the stabilities of cathode materials are improved. One of the major drawbacks of the single-crystal cathodes is that their achievable capacity is lower than that of the same composition polycrystalline cathodes. Although it is widely accepted that the large crystal size of single-crystal cathodes might be the main reason for their low capacity, a systematic study to verify all possible rationales is absent. In this work, we regulated the crystal size of a single-crystal LiNiO2 to investigate its relation to capacity for the first time. It was established that among the sizes studied, a 400 nm-sized single crystal LiNiO2 achieved high capacity, ∼240 mA h/g at 0.1 C, which is comparable to that of its polycrystalline counterpart. It is the first report that such a high capacity is obtained in a single crystal. Also, in our results, with increasing crystal size, a capacity decline was recorded as expected. Interestingly, it is first found that capacity loss occurs only in the high-lithium-composition region (x > 0.8 in LixNiO2), and polarization becomes high only in the same region upon increasing crystal size. This implies that kinetics of the region is significantly affected by the crystal size. Also, high capacity can be achieved in large single-crystal LixNiO2 once the region's kinetics is optimized. In terms of capacity retention, large single-crystal LiNiO2 exhibits the highest stability. Accordingly, high capacity can be achieved when the crystal size is reduced by trading-off its cycling stability. In order to achieve both high capacity and stability, LiF surface coating was conducted on the small single-crystal LiNiO2. It was shown that the LiF coating can effectively protect against capacity degradation, and the capacity retention by such small single-crystal LiNiO2 can be made even better than that of large crystal LiNiO2. Therefore, both high capacity and cycle retention were achieved in single-crystal LiNiO2 by reducing its crystal size and LiF surface coating. © 2024 American Chemical Society
Interplanar ferromagnetism enhanced ultrawide zero thermal expansion in kagome cubic intermetallic (Zr,Nb)Fe2
(American Chemical Society, 2023-07-25) Sun, YM; Cao, Y; Hu, SX; Avdeev, M; Wang, CW; Khmelevskyi, S; Ren, Y; Lapidus, SH; Chen, X; Li, Q; Deng, JX; Miao, J; Lin, K; Kuang, XO; Xing, XR
A cubic metal exhibiting zero thermal expansion (ZTE) over a wide temperature window demonstrates significant applications in a broad range of advanced technologies but is extremely rare in nature. Here, enabled by high-temperature synthesis, we realize tunable thermal expansion via magnetic doping in the class of kagome cubic (Fd-3m) intermetallic (Zr,Nb)Fe2. A remarkably isotropic ZTE is achieved with a negligible coefficient of thermal expansion (+0.47 × 10-6 K-1) from 4 to 425 K, almost wider than most ZTE in metals available. A combined in situ magnetization, neutron powder diffraction, and hyperfine Mössbauer spectrum analysis reveals that interplanar ferromagnetic ordering contributes to a large magnetic compensation for normal lattice contraction upon cooling. Trace Fe-doping introduces extra magnetic exchange interactions that distinctly enhance the ferromagnetism and magnetic ordering temperature, thus engendering such an ultrawide ZTE. This work presents a promising ZTE in kagome metallic materials. © 2023 American Chemical Society.
Defining the structural characteristics of annexin V binding to a mimetic apoptotic membrane
(Springer Nature, 2015-08-14) Lu, JX; Le Brun, AP; Chow, SH; Shiota, T; Wang, B; Lin, TW; Liu, GS; Shen, HH
Annexin V is of crucial importance for detection of the phosphatidylserine of apoptotic cell membranes. However, the manner in which different amounts of phosphatidylserine at the membrane surface at different stages of apoptosis contribute to binding of annexin V is unclear. We have used a quartz crystal microbalance combined with dissipative monitoring (QCM–D) and neutron reflectivity to characterize binding of human annexin V to supported bilayers of different phospholipid composition. We created model apoptotic bilayers of 1-palmitoyl-2-oleoyl-sn-glycerophosphocholine and 1-palmitoyl-2-oleoyl-sn-glycerophosphoserine (POPS) in the ratios 19:1, 9:1, 6.7:1, 4:1, 3:1, and 2:1 (w/w) in the presence of 2.5 mM CaCl2. QCM–D data revealed that annexin V bound less to supported fluid lipid bilayers with higher POPS content (>25 % POPS). Neutron reflectivity was used to further characterize the detailed composition of lipid bilayers with membrane-bound annexin V. Analysis confirmed less annexin V binding with higher POPS content, that bound annexin V formed a discrete layer above the lipid bilayer with little effect on the overall structure of the membrane, and that the thickness and volume fraction of the annexin V layer varied with POPS content. From these results we show that the POPS content of the outer surface of lipid bilayers affects the structure of membrane-bound annexin V. © 2024 Springer Nature.
In operando study of the hydrogen-induced switching of magnetic anisotropy at the Co/Pd Interface for magnetic hydrogen gas sensing
(American Chemical Society, 2019-08-02) Causer, GL; Kostylev, M; Cortie, DL; Lueng, C; Callori, SJ; Wang, XL; Klose, F
Heterostructures exhibiting perpendicular magnetic anisotropy (PMA) have traditionally served the magnetic recording industry. However, an opportunity exists to expand the applications of PMA heterostructures into the realm of hydrogen sensing using ferromagnetic resonance (FMR) by exploiting the hydrogen-induced modifications to PMA that occur at the interface between Pd and a ferromagnet. Here, we present the first in operando depth-resolved study of the in-plane interfacial magnetization of a Co/Pd film which features tailorable PMA in the presence of hydrogen gas. We combine polarized neutron reflectometry with in situ FMR to explore how the absorption of hydrogen at the Co/Pd interface affects the heterostructures spin-resonance condition during hydrogen cycling. Experimental data and modeling reveal that the Pd layer expands when exposed to hydrogen gas, while the in-plane magnetic moment of the Co/Pd film increases as the interfacial PMA is reduced to affect the FMR frequency. This work highlights a potential route for magnetic hydrogen gas sensing. © 2019 American Chemical Society.
Solvent-free mechanochemical synthesis of organic proton conducting salts incorporating imidazole and dicarboxylic acids
(Elsevier, 2023-05) Zhou, YT; Koedtruad, A; Tan, ZH; Zhang, D; Bao, LX; Yue, YJ; Wu, JY; Xu, JP; Xia, YG; Yin, W; Avdeev, M; Kan, WH; Kamiyama, T; Miao, P
Solventless mechanochemical synthesis by manual grinding was applied to grow organic proton conducting salts, imidazole-succinic acid (C3H4N2-HOOC(CH2)2COOH) and imidazole-glutaric acid (C3H4N2-HOOC(CH2)3COOH). This synthesis method induces crystallization and provides the phase-pure compounds. The compounds exhibit different electric conducting behavior and activation energies Ea compared with the reported single crystals obtained from the solution method. The difference in conducting property can be related to intrinsic defects and structural disorder introduced by mechanochemical grinding, indicating that the mechanochemical method bears strong capability for tuning conductivities. Moreover, complete deuteration of the organic salts is achieved by the method. The mechanochemical synthesis of organic salts also holds high potential for the actual industrialized large-scale production. © 2023 Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

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