다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Each cell of a battery stores electrical energy as chemical energy in two electrodes, a reductant (anode) and an oxidant (cathode), separated by an electrolyte that transfers the ionic component of the chemical reaction inside the cell and forces the electronic component outside the battery. The output on discharge is an external electronic current I at a voltage V for a time Δt. The chemical reaction of a rechargeable battery must be reversible on the application of a charging I and V. Critical parameters of a rechargeable battery are safety, density of energy that can be stored at a specific power input and retrieved at a specific power output, cycle and shelf life, storage efficiency, and cost of fabrication. Conventional ambient-temperature rechargeable batteries have solid electrodes and a liquid electrolyte. The positive electrode (cathode) consists of a host framework into which the mobile (working) cation is inserted reversibly over a finite solid–solution range. The solid–solution range, which is...

The Li-ion rechargeable battery: a perspective.

Li-ion battery technology has become very important in recent years as these batteries show great promise as power sources that can lead us to the electric vehicle (EV) revolution. The development of new materials for Li-ion batteries is the focus of research in prominent groups in the field of materials science throughout the world. Li-ion batteries can be considered to be the most impressive success story of modern electrochemistry in the last two decades. They power most of today's portable devices, and seem to overcome the psychological barriers against the use of such high energy density devices on a larger scale for more demanding applications, such as EV. Since this field is advancing rapidly and attracting an increasing number of researchers, it is important to provide current and timely updates of this constantly changing technology. In this review, we describe the key aspects of Li-ion batteries: the basic science behind their operation, the most relevant components, anodes, cathodes, electrolyte solutions, as well as important future directions for R&D of advanced Li-ion batteries for demanding use, such as EV and load-leveling applications.

Challenges in the development of advanced Li-ion batteries: a review

Li-ion battery materials: present and future

We report the vibrational spectra of numerous 4-volt cathode materials, the transition metal oxides which are potential materials for advanced Li-ion batteries. They provide high specific energy density, high voltage, and remarkable reversibility for lithium intercalation-deintercalation process. Studied were carried out by Raman and FTIR spectroscopies. Oxides such as LiMn2O4, LiNiVO4, LiCoVO4 spinels, LiMeO2 (Me=Co, Ni, Cr) layered compounds and their mixed compounds have been investigated. The local environment of cations against oxygen neighboring atoms has been determined by considering tetrahedral and octahedral units building the lattice. Structural modifications induced by the intercalation-deintercalation process, by the cation substitution, or by the low-temperature preparation route are also examined. The results are compared with those of end members.

Vibrational Spectroscopic Studies of the Local Environment in 4-Volt Cathode Materials

The glass-crystalline transformation induced by laser irradiation is studied in MoO3. Before crystallization we have found that the system evolves from a low temperature glass phase to a high temperature glass phase. The crystallization kinetics depend strongly on the initial irradiation power. The power densities needed to induce the phase transformations, of the order of 15 W/mm2, are relatively low and suggest the possibility of using this material as a data storage medium.

Laser-induced structural transformations in MoO3 investigated by Raman spectroscopy

EDTA as chelating agent for sol-gel synthesis of spinel LiMn2O4 cathode material for lithium batteries

We present the synthesis, characterization and electrode behaviour of LiMn2-yCoyO4 (0 <= y <= 1) spinel oxides prepared by the wet-chemical route assisted by carboxylic acid. The phase evolution was studied as a function of the cobalt substitution and the modification on the intercalation and deintercalation of Li ions. Characterization methods include TG-DTA, XRD, SEM, Raman, FTIR, and SQUID. LiMn2-yCoyO samples crystallize with the cubic spinel-like structure (Fd3m S.G.). Raman scattering and FT-infrared spectroscopy indicate that the vibrational mode frequencies and relative intensities of the bands are sensitive to the covalency of the (Co, Mn)-O bonds. MEB micrographs show that the particle dimension of the LiMn2-yCoyO4 powders ranges in the sub-micron-sized domain with a narrow grain-size distribution. The overall electrochemical capacity of LiMn2-yCoyO4 oxides have been reduced due to the 3d(6) metal substitution. However, a more stable charge-discharge cycling performances has been observed when the electrodes are charged up to 4.3 V as compared to the performance of the native oxide. For such a cut-off voltage, the charge capacity of the Li//LiMn1.8CO0.2O4 cell is ca. 101 mA h/g. Differences and similarities between LiMn2O4 and Co-substituted oxides are discussed there from. (c) 2006 Elsevier B.V All rights reserved.

LiMn2-yCOyO4 (0 <= y <= 1) intercalation compounds synthesized from wet-chemical route

Among the compounds of the olivine family, LiMPO4 with M = Fe, Mn, Ni, or Co, only LiFePO4 is currently used as the active element of positive electrodes in lithium-ion batteries. However, intensive research devoted to other elements of the family has recently been successful in significantly improving their electrochemical performance, so that some of them are now promising for application in the battery industry and outperform LiFePO4 in terms of energy density, a key parameter for use in electric vehicles in particular. The purpose of this review is to acknowledge the current state of the art and the progress that has been made recently on all the elements of the family and their solid solutions. We also discuss the results from the perspective of their potential application in the industry of Li-ion batteries.

https://www.mdpi.com/2313-0105/4/3/39/pdf

Christian M. Julien

Papers

Vibrational Spectroscopic Studies of the Local Environment in 4-Volt Cathode Materials

Laser-induced structural transformations in MoO3 investigated by Raman spectroscopy

EDTA as chelating agent for sol-gel synthesis of spinel LiMn2O4 cathode material for lithium batteries

LiMn2-yCOyO4 (0 <= y <= 1) intercalation compounds synthesized from wet-chemical route

Olivine Positive Electrodes for Li-Ion Batteries: Status and Perspectives