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

Study of the Li-insertion/extraction process in LiFePO4/FePO4

The electronic structure of LiFePO4 and delithiated FePO4 is revisited in the light of the previous calculations taking into account the coulomb correlation potential for d-electrons. The nature of the optical transitions across the energy gap is investigated. In LiFePO4, these are intra-atomic Fe2+−Fe3+ transitions suffering a strong Franck−Condon effect due to the local distortion of the lattice in FePO4, which is indirect evidence of the formation of a small polaron. This situation contrasts with that met in the much more covalent delithiated phase, where the optical transition across the energy gap is associated with a transfer of an electron from the p-states of the oxygen to the d-states of iron ions. The small polarons in LiFePO4 are associated with the presence of Fe3+ ions introduced by native defects in relative concentration [Fe3+]/[Fe2++Fe3+] = 3 × 10-3 in the samples known to be optimized with respect to their electrochemical properties. The nearest iron neighbors around the central polaron s...

Electronic, Optical, and Magnetic Properties of LiFePO4: Small Magnetic Polaron Effects

Lithium batteries are electrochemical devices that are widely used as power sources. This history of their development focuses on the original development of lithium-ion batteries. In particular, we highlight the contributions of Professor Michel Armand related to the electrodes and electrolytes for lithium-ion batteries.

Brief History of Early Lithium-Battery Development.

Surface analysis of lithium manganese oxides synthesized by the melt-impregnation method has been made by x-ray photoelectron spectroscopy. These results revealed the change in the average oxidation state of Mn cations upon lithium substitution in Li 1+δ Mn 2-δ O 4 spinels. Studies of the local structure characterized by Raman scattering show the Mn-O bonding evolution as a function of the replacement of manganese cations. Modification in the trigonal distortion of MnO 6 octahedra is evidenced by insertion of lithium ions into the octahedral holes of the [B 2 ]O 4 spinel framework.

XPS and Raman spectroscopic characterization of LiMn2O4 spinels

We present the synthesis, characterization, and electrode behavior of LiNi0.5Mn1.5O4 spinels prepared by the wet-chemical method via citrate precursors. The phase evolution was studied as a function of nickel substitution and upon intercalation and deintercalation of Li ions. Characterization methods include X-ray diffraction, SEM, Raman, Fourier transform infrared, superconducting quantum interference device, and electron spin resonance. The crystal chemistry of LiNi0.5Mn1.5O4 appears to be strongly dependent on the growth conditions. Both normal-like cubic spinel [Fd3m space group (SG)] and ordered spinel (P4132 SG) structures have been formed using different synthesis routes. Raman scattering and infrared features indicate that the vibrational mode frequencies and relative intensities of the bands are sensitive to the covalency of the (Ni, Mn)-O bonds. Scanning electron microscopy (SEM) micrographs show that the particle size of the LiNi0.5Mn1.5O4 powders ranges in the submicronic domain with a narrow grain-size distribution. The substitution of the 3d8 metal for Mn in LiNi0.5Mn1.5O4 oxides is beneficial for its charge–discharge cycling performance. For a cut-off voltage of 3.5–4.9 V, the electrochemical capacity of the Li//LiNi0.5Mn1.5O4 cell is ca. 133 mAh/g during the first discharge. Differences and similarities between LiMn2O4 and LiNi0.5Mn1.5O4 oxides are discussed.

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Christian M. Julien

Papers

Study of the Li-insertion/extraction process in LiFePO4/FePO4

Electronic, Optical, and Magnetic Properties of LiFePO4: Small Magnetic Polaron Effects

Brief History of Early Lithium-Battery Development.

XPS and Raman spectroscopic characterization of LiMn2O4 spinels

Structure and insertion properties of disordered and ordered LiNi0.5Mn1.5O4 spinels prepared by wet chemistry