Ahmed M. Hashem

Smart materials for energy storage in Li-ion batteries

The natural inhabitants of the gastrointestinal tract play a key role in the maintenance of human health. Over the last century, the changes on the behavior of our modern society have impacted the diversity of this gut microbiome. Among the strategies to restore gut microbial homeostasis, the use of probiotics has received a lot of attention. Probiotics are living microorganisms that promote the host health when administered in adequate amounts. Its popularity increase in the marketplace in the last decade draws the interest of scientists in finding suitable methods capable of delivering adequate amounts of viable cells into the gastrointestinal tract. Encapsulation comes into the scene as an approach to enhance the cells survival during processing, storage and consumption. This paper provides a comprehensive perspective of the probiotic field at present time focusing on the academia and industry scenarios in the past few years in terms of encapsulation technologies employed and research insights including patents. The analysis of the encapsulation technologies considering food processing costs and payload of viable bacteria reaching the gastrointestinal tract would result into successful market novelties. There is yet a necessity to bridge the gap between academia and industry.

Structural and electrochemical properties of LiNi1/3Co1/3Mn1/3O2 material prepared by a two-step synthesis via oxalate precursor

LiNi1/3Co1/3Mn1/3O2 (LNMCO) powders were formed by a two-step synthesis including preparation of an oxalate precursor by “chimie douce” followed by a solid-state reaction with lithium hydroxide. The product was characterized by TG-DTA, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), Raman spectroscopy, electron spin resonance (ESR), and SQUID magnetometry. XRD data revealed well-crystallized layered LNMCO with α-NaFeO2-type structure (R-3xa0m space group). Morphology studied by SEM and TEM shows submicronic particles of 400–800xa0nm with a tendency to agglomerate. The local structure investigated by vibrational spectroscopy (FTIR, Raman), ESR, and SQUID measurements confirms the well-crystallized lattice with a cation disorder of 2.6% Ni2+ ions in Li(3b) sites. Electrochemical tests were carried out in the potential range 2.5–4.5xa0V vs. lithium metal on samples heated at 900xa0°C for 12xa0h. Initial discharge capacity is 154 mAh/g at C/5, while a capacity of 82 mAh/g is still delivered at 10 C by the two-step synthesized LiNi1/3Co1/3Mn1/3O2 as cathode material.

Preparation, characterization and electrochemical performance of γ-MnO2 and LiMn2O4 as cathodes for lithium batteries

The spinel LiMn2O4 is a very promising cathode material with economical and environmental advantages. LiMn2O4 materials have been synthesized by solid state method using γ-MnO2 as manganese source, and Li2CO3 or LiNO3 as Li sources. γ-MnO2 is a commercial battery grade electrolytic manganese dioxide (TOSOH-Hellas GH-S) and LiMn2O4 samples were synthesized at a calcinations temperature up to 800 °C. γ-MnO2 and LiMn2O4 samples were characterized by X-ray diffraction, thermal and electrochemical measurements. X-ray powder diffraction of as prepared LiMn2O4 showed a well-defined highly pure spinel single phase. The electrochemical performance of LiMn2O4 and its starting material γ-MnO2 was evaluated through cyclic voltammetry, galvanostatic (constant current charge-discharge cycling) The electrochemical properties in terms of cycle performance were also discussed.γ-MnO2 showed fairly high initial capacity of about 200 mAhg−1 but poor cycle performance. LiMn2O4 samples showed fairly low initial capacity but good cycle performance.