Browsing by Author "Hou, J"

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    Mass spectrometry and Monte Carlo Method mapping of nanoparticle ligand shell morphology
    (Springer Nature, 2018-10-26) Luo, Z; Shao, YF; Darwish, TA; Wang, Y; Hou, J; Stellacci, F
    Janus, patchy, stripe-like, or random arrangements of molecules within the ligand shell of nanoparticles affect many properties. Among all existing ligand shell morphology characterization methods, the one based on mass spectroscopy is arguably the simplest. Its greatest limitation is that the results are qualitative. Here, we use a tailor-made Monte Carlo type program that fits the whole MALDI spectrum and generates a 3D model of the ligand shell. Quantitative description of the ligand shell in terms of nearest neighbor distribution and characteristic length scale can be readily extracted by the model, and are compared with the results of other characterization methods. A parameter related to the intermolecular interaction is extracted when this method is combined with NMR. This approach could become the routine method to characterize the ligand shell morphology of many nanoparticles and we provide an open access program to facilitate its use. © The Authors - Creative Commons Attribution 4.0
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    Unlocking fast and reversible sodium intercalation in NASICON Na4MnV(PO4)3 by fluorine substitution
    (Elsevier, 2021-11) Hou, J; Hadouchi, M; Sui, L; Liu, J; Tang, M; Kan, WH; Avdeev, M; Zhong, G; Liao, YK; Lai, YH; Chu, YH; Lin, HJ; Chen, CT; Hu, ZW; Huang, YH; Ma, J
    The exploitation of high energy and high power densities cathode materials for sodium ion batteries is a challenge. Na-super-ionic-conductor (NASICON) Na4MnV(PO4)3 is one of promising high-performance and low-cost cathode materials, however, still suffers from not reaching the theoretical capacity, low rate capability, and poor cycling stability. In this work, we deploy a novel sodium-deficient NASICON fluorinated phosphate cathode material for sodium ion batteries which demonstrates, notably, high energy and high power densities concomitant with high sodium diffusion kinetics. The enhanced performance of this novel Na3.85⬜0.15MnV(PO3.95F0.05)3 cathode was evidenced by demonstrating a relatively high energy density of ∼380 Wh kg−1 at low rate with much improved rate capability compared to non-doped Na4MnV(PO4)3, and long cycling life over 2000 cycles at high current rates. The structural investigation during battery operation using in situ x-ray diffraction (XRD) reveals bi-phase mechanism with high structural reversibility. The combined XRD and 23Na nuclear magnetic resonance (NMR) analyses demonstrate that the sodium extraction/insertion from Na2 is faster than Na1 site. These findings open promising prospects for unlocking of high energy and high power densities of NASICON phosphate materials by fluorine substitution towards high-performance sodium ion batteries. © 2021 Elsevier B.V.