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

Resonant electronic Raman scattering has been measured at low temperatures in ZnTe crystals doped with Li acceptors using a tunable dye laser. The LO phonon sideband of the electronic transition band has shown the shown the resonant behaviour as the zero-phonon band. This is interpreted in terms of a configuration-coordinate model in which an exciton bound to the acceptor acts as dominant intermediate state. Distinction between the resonant Raman and luminescence processes in fairly high doped crystals has been examined experimentally.

Resonant Raman scattering and luminescence in Li-doped ZnTe

With the aim to reduce the entire cost of lithium-ion batteries and to diminish the environmental impact, the extract of broccoli is used as a strong benign reducing agent for potassium permanganate to synthesize α-KyMnO2 cathode material with pure nanostructured phase. Material purity is confirmed by X-ray powder diffraction and thermogravimetric analyses. Images of transmission electron microscopy show samples with a spider-net shape consisting of very fine interconnected nanoneedles. The nanostructure is characterized by crystallite of 4.4 nm in diameter and large surface area of 160.7 m2 g-1. The material delivers an initial capacity of 211 mAh g-1 with high Coulombic efficiency of 99% and 82% capacity retention after 100 cycles. Thus, α-KyMnO2 synthesized via a green process exhibits very promising electrochemical performance in terms of initial capacity, cycling stability and rate capability.

https://www.mdpi.com/1996-1944/13/6/1269/pdf

Synthesis of High Surface Area α-KyMnO2 Nanoneedles Using Extract of Broccoli as Bioactive Reducing Agent and Application in Lithium Battery.

Recently, increasing interest has focused on DMS materials in which Mn is replaced by other transition metal ions: iron and cobalt. In Section 2 we will present particularly interesting properties of HgSe:Fe, connected with the peculiar energy position of d-derived Fe states in its band structure. Section 3 will be devoted to description of some optical and magnetic properties of Cd1-xFex Te. The Jahn-Teller coupling piays an important role in the explanation of the observed effects. In Section 4 we will discuss some result for Co-based DMS. Finally, the study of Fe2+ in lowered symmetry environment, which is realized in alloys like (Cd1-xFex)(Te1-ySey), will be presented in Section 5.

II?VI Semiconductors Doped with Transition Metals Other Than Mn

Apart from crystalline materials, the second class of solid electrolytes is the family of amorphous conductors which in contrast more closely resemble liquid electrolytes than crystalline solids. It is easier to define an amorphous state by saying what it is not than by precisely specifying what it is. Amorphous materials are noncrystalline substances. They lack long-range periodic ordering of their constituent atoms. That is not to say that amorphous materials are completely disordered on the atomic scale. Local chemistry provides almost rigorous bond-length, and to a lesser extent, bond-angle constraints on the nearest-neighbor environment. For instance, unlike amorphous metals, amorphous semiconductors do not consist of close-packed atoms, but rather they contain covalently bonded atoms arranged in an open network with correlations in ordering up to the third- or fourth-nearest neighbors. The short-range order is directly responsible for observable semiconductor properties such as optical absorption edges and activated electrical conductivities.

Christian M. Julien

Papers

Resonant Raman scattering and luminescence in Li-doped ZnTe

Synthesis of High Surface Area α-KyMnO2 Nanoneedles Using Extract of Broccoli as Bioactive Reducing Agent and Application in Lithium Battery.

II?VI Semiconductors Doped with Transition Metals Other Than Mn

Materials for electrolyte: Fast-ion-conducting glasses

Polypyrrole-Covered MnO2 as Electrode Material for Hydrid Supercapacitor