Synthesis and crystal chemistry of the NaMSO4F family (M = Mg, Fe, Co, Cu, Zn)

ChemInform 01/2012; 14:15-20. DOI: 10.1016/j.solidstatesciences.2011.09.004

ABSTRACT Our work in metal fluorosulphate chemistry, which was triggered by the discovery of the tavorite-phase of LiFeSO4F, has unveiled many novel Li- and Na-based phases with desirable electrochemical and/or transport properties. Further exploring this rich crystal chemistry, we have synthesized the Na-based magnesium, copper and zinc fluorosulphates, which crystallise in the maxwellite (tavorite-like framework) structure just as their Fe and Co counterparts, which were previously reported. These phases show ionic conductivities in the range of ∼10−7 S cm−1 or ∼10−11 S cm−1 depending upon their synthesis process and no reversible electrochemical activity versus Na.

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    ABSTRACT: NaFeSO4F and NaCoSO4F crystallize in the maxwellite crystal structure and consist of one-dimensional chains of corner-sharing MO4F2 octahedra linked together through F atoms sitting in a trans configuration with respect to each other. Magnetic susceptibility measurements and low-temperature powder neutron diffraction indicate that both the Fe- and Co-based phases establish G-type antiferromagnetic ground states below 36 and 29 K, respectively. We discuss the obtained magnetic structure in the context of the local anisotropy of the two magnetic ions.
    Physical review. B, Condensed matter 03/2012; 85(9). · 3.66 Impact Factor
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    ABSTRACT: Designed as high capacity alloy host for Na-ion chemistry, forest of Sn nanorods with a unique core-shell structure were synthesized on viral scaffolds, which were genetically engineered to ensure a nearly vertical alignment upon self-assembling onto metal substrate. The interdigital spaces thus formed between individual rods effectively accommodated the volume expansion and contraction of the alloy upon sodiation/de-sodiation, while additional carbon coating engineered over these nanorods further suppressed Sn-aggregation during extended electrochemical cycling. Due to the unique nano-hierarchy of multiple functional layers, the resultant 3D nanoforest of C/Sn/Ni/TMV1cys, binder-free composite electrode already and evenly assembled on stainless steel current collector, exhibited supreme capacity utilization and cycling stability toward Na-ion storage and release. An initial capacity of 722 mAh (g Sn)-1 along with 405 mAh (g Sn)-1 retained after 150 deep cycles demonstrates the longest-cycling nano-Sn anode material for Na-ion batteries reported in literatures to date and marks a significant performance improvements for neat Sn material as alloy host for Na-ion chemistry.
    ACS Nano 03/2013; · 12.03 Impact Factor