Synthesis and crystal chemistry of the NaMSO4F family (M = Mg, Fe, Co, Cu, Zn)
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.
Article: Sodium-Ion Batteries[Show abstract] [Hide abstract]
ABSTRACT: The status of ambient temperature sodium ion batteries is reviewed in light of recent developments in anode, electrolyte and cathode materials. These devices, although early in their stage of development, are promising for large-scale grid storage applications due to the abundance and very low cost of sodium-containing precursors used to make the components. The engineering knowledge developed recently for highly successful Li ion batteries can be leveraged to ensure rapid progress in this area, although different electrode materials and electrolytes will be required for dual intercalation systems based on sodium. In particular, new anode materials need to be identified, since the graphite anode, commonly used in lithium systems, does not intercalate sodium to any appreciable extent. A wider array of choices is available for cathodes, including high performance layered transition metal oxides and polyanionic compounds. Recent developments in electrodes are encouraging, but a great deal of research is necessary, particularly in new electrolytes, and the understanding of the SEI films. The engineering modeling calculations of Na-ion battery energy density indicate that 210 Wh kg−1 in gravimetric energy is possible for Na-ion batteries compared to existing Li-ion technology if a cathode capacity of 200 mAh g−1 and a 500 mAh g−1 anode can be discovered with an average cell potential of 3.3 V.Advanced Functional Materials 02/2013; 23(8):947-958. · 10.44 Impact Factor
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ABSTRACT: The ever-increasing demand for high-performing, economical, and safe power storage for portable electronics and electric vehicles stimulates R&D in the field of chemical power sources. In the past two decades, lithium-ion technology has proven itself a most robust technology, which delivers high energy and power capabilities. At the same time, current technology requires that the energy and power capabilities of Li-ion batteries be ‘beefed up’ beyond the existing state of the art. Increasing the battery voltage is one of the ways to improve battery energy density; in Li-ion cells, the objective of current research is to develop a 5-volt cell, and at the same time to maintain high specific charge capacity, excellent cycling, and safety. Since current anode materials possess working potentials fairly close to the potential of a lithium metal, the focus is on the development of cathode materials. This work reviews and analyzes the current state of the art, achievements, and challenges in the field of high-voltage cathode materials for Li-ion cells. Some suggestions regarding possible approaches for future development in the field are also presented.Advanced Energy Materials 01/2012; 2(8):922–939. · 14.39 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