Cairo University

About: Cairo University is a education organization based out in Giza, Egypt. It is known for research contribution in the topics: Population & Medicine. The organization has 33532 authors who have published 55581 publications receiving 792654 citations. The organization is also known as: Fuad I University & King Fuad I University.

Raman Spectroscopy in Lithium–Oxygen Battery Systems

Abstract: Electrochemical processes in lithium–oxygen (Li–O2 or Li–air) batteries are complex, with chemistry depending on cycling conditions, electrode materials and electrolytes. In non-aqueous Li–O2 cells, reversible lithium peroxide (Li2O2) and irreversible parasitic products (i.e., LiOH, Li2CO3, Li2O) are common. Superoxide intermediates (O2−, LiO2) contribute to the formation of these species and are transiently stable in their own right. While characterization techniques like XRD, XPS and FTIR have been used to observe many Li–O2 species, these methods are poorly suited to superoxide detection. Raman spectroscopy, however, may uniquely identify superoxides from O−O vibrations. The ability to fingerprint Li–O2 products in situ or ex situ, even at very low concentrations, makes Raman an essential tool for the physicochemical characterization of these systems. This review contextualizes the application of Raman spectroscopy and advocates for its wider adoption in the study of Li–O2 batteries.

A Simple Model of Double-Loop Hysteresis Behavior in Memristive Elements

Abstract: This brief investigates the double-loop hysteresis behavior in memristive elements. Here, we propose a very simple dimensionless equation to model the double-loop behavior and then show how physical voltage- and current-controlled memristor models can be derived. Furthermore, we introduce the incremental/decremental positive/negative memristance/transmemristance and present circuit emulators which are capable of emulating these devices. Experimental results are given.