John M. Parker

Bio: John M. Parker is an academic researcher from University of Sheffield. The author has contributed to research in topics: Fluoride & Scintillator. The author has an hindex of 21, co-authored 52 publications receiving 3129 citations.

Floppy modes in crystalline and amorphous silicates

Abstract: In this chapter we have outlined a number of feature of the RUM flexibility of crystalline networks of linked tetrahedra and octahedra. As we have stressed, the initial value of the RUM approach was to give an understanding of the origin and characteristics of displacive phase transitions. However, since the RUM approach also gives use the means to understand the whole area of low-frequency dynamics of network structures containing rigid units, and the insights from this have been useful to understand dynamically disordered crystalline phases, zeolites, and now silica glass.

Redox and clustering of iron in silicate glasses

Abstract: Soda–lime–silica glasses (70 mol% SiO2:15 mol% Na2O:15 mol% CaO) containing 0.1–5 mol% Fe2O3 have been investigated using optical absorption spectroscopy, Mossbauer spectroscopy, and wet chemical analysis. Iron redox ratios measured by these different techniques are in agreement. Samples were annealed at 550°C for 1 h in air. As the iron content increases more of the iron ions are in adjacent sites and this manifests itself as changes in the optical and Mossbauer spectra. For example an absorption peak in the visible region which appears with increasing iron content can be assigned to Fe2+–O2−–Fe3+ interactions. Mossbauer parameters indicate that, as Fe2+ and Fe3+ ions cluster, their co-ordination becomes more tetrahedral although the iron concentration has no effect on the Fe2+/ΣFe ratio in the glasses studied. Estimates of the proportion of Fe3+ ions in adjacent sites have been made using Mossbauer data.

Issues and challenges facing rechargeable lithium batteries

Abstract: Technological improvements in rechargeable solid-state batteries are being driven by an ever-increasing demand for portable electronic devices. Lithium-ion batteries are the systems of choice, offering high energy density, flexible and lightweight design, and longer lifespan than comparable battery technologies. We present a brief historical review of the development of lithium-based rechargeable batteries, highlight ongoing research strategies, and discuss the challenges that remain regarding the synthesis, characterization, electrochemical performance and safety of these systems.

Nonaqueous liquid electrolytes for lithium-based rechargeable batteries.

Abstract: 2.1. Solvents 4307 2.1.1. Propylene Carbonate (PC) 4308 2.1.2. Ethers 4308 2.1.3. Ethylene Carbonate (EC) 4309 2.1.4. Linear Dialkyl Carbonates 4310 2.2. Lithium Salts 4310 2.2.1. Lithium Perchlorate (LiClO4) 4311 2.2.2. Lithium Hexafluoroarsenate (LiAsF6) 4312 2.2.3. Lithium Tetrafluoroborate (LiBF4) 4312 2.2.4. Lithium Trifluoromethanesulfonate (LiTf) 4312 2.2.5. Lithium Bis(trifluoromethanesulfonyl)imide (LiIm) and Its Derivatives 4313

Lithium metal anodes for rechargeable batteries

Abstract: Lithium (Li) metal is an ideal anode material for rechargeable batteries due to its extremely high theoretical specific capacity (3860 mA h g−1), low density (0.59 g cm−3) and the lowest negative electrochemical potential (−3.040 V vs. the standard hydrogen electrode). Unfortunately, uncontrollable dendritic Li growth and limited Coulombic efficiency during Li deposition/stripping inherent in these batteries have prevented their practical applications over the past 40 years. With the emergence of post-Li-ion batteries, safe and efficient operation of Li metal anodes has become an enabling technology which may determine the fate of several promising candidates for the next generation energy storage systems, including rechargeable Li–air batteries, Li–S batteries, and Li metal batteries which utilize intercalation compounds as cathodes. In this paper, various factors that affect the morphology and Coulombic efficiency of Li metal anodes have been analyzed. Technologies utilized to characterize the morphology of Li deposition and the results obtained by modelling of Li dendrite growth have also been reviewed. Finally, recent development and urgent need in this field are discussed.

Lithium battery chemistries enabled by solid-state electrolytes

Abstract: Solid-state electrolytes are attracting increasing interest for electrochemical energy storage technologies. In this Review, we provide a background overview and discuss the state of the art, ion-transport mechanisms and fundamental properties of solid-state electrolyte materials of interest for energy storage applications. We focus on recent advances in various classes of battery chemistries and systems that are enabled by solid electrolytes, including all-solid-state lithium-ion batteries and emerging solid-electrolyte lithium batteries that feature cathodes with liquid or gaseous active materials (for example, lithium–air, lithium–sulfur and lithium–bromine systems). A low-cost, safe, aqueous electrochemical energy storage concept with a ‘mediator-ion’ solid electrolyte is also discussed. Advanced battery systems based on solid electrolytes would revitalize the rechargeable battery field because of their safety, excellent stability, long cycle lives and low cost. However, great effort will be needed to implement solid-electrolyte batteries as viable energy storage systems. In this context, we discuss the main issues that must be addressed, such as achieving acceptable ionic conductivity, electrochemical stability and mechanical properties of the solid electrolytes, as well as a compatible electrolyte/electrode interface. This Review details recent advances in battery chemistries and systems enabled by solid electrolytes, including all-solid-state lithium-ion, lithium–air, lithium–sulfur and lithium–bromine batteries, as well as an aqueous battery concept with a mediator-ion solid electrolyte.