共查询到20条相似文献,搜索用时 0 毫秒
1.
《Green Chemistry Letters and Reviews》2013,6(2):135-142
Abstract Battery technology is an important anthropogenic source of the heavy metals which are highly threatening to human health. A category of rechargeable lithium batteries that is of great interest is the set of batteries where the cathode material is a lithium iron phosphate (LiFePO4). LiFePO4 is an environmentally friendly and safe lithium-ion battery cathode material, but it has a key limitation, and that is its extremely low-electronic conductivity, a problem that can be greatly overcome by zinc-doping LiFePO4. For the first time to our knowledge, a low-temperature method, that is advantageous both economically and technologically, for the synthesis of a zinc-doped LiFePO4 is presented. Since the method appears to be applicable for synthesizing various zinc-doped LiFePO4 compounds with the general formula LiFe1?x Zn x PO4 (0<x<1), it is very promising for the production of a green cathode material for lithium-ion batteries. 相似文献
2.
3.
Li CC Yin XM Li QH Chen LB Wang TH 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(5):1596-1604
Two kinds of topochemical conversion routes from cobalt hydroxide precursors to cobalt oxide-based porous nanostructures are presented: pyrolysis in air and hydrothermal treatment by the Kirkendall diffusion effect. These cobalt hydroxide precursors were synthesized by a simple hydrothermal approach with sodium acetate as mineralizer at 200 °C. Detailed proof indicates that the process of cobalt hydroxide precursor growth is dominated by a nucleation, dissolution, renucleation, growth, and exfoliation mechanism. By the topochemical conversion processes several Co(3)O(4) nanostructures, such as cobalt oxide-coated cobalt hydroxide carbonate nanowires, cobalt oxide nanotubes, hollow cobalt oxide spheres, and porous cobalt oxide nanowires, have been synthesized. The obtained Co(3)O(4) nanostructures have also been evaluated as the anode materials in lithium-ion batteries. It was found that the as-prepared Co(3)O(4) nanostructures exhibited high reversible capacity and good cycle performance due to their porous structure and small size. 相似文献
4.
5.
The mechanism of Lewis acid catalysed hetero‐Michael addition reactions of weakly basic nucleophiles to α,β‐unsaturated ketones was investigated. Protons, rather than metal ions, were identified as the active catalysts. Other mechanisms have been ruled out by analyses of side products and of stoichiometric enone–catalyst mixtures and by the use of radical inhibitors. No evidence for the involvement of π‐olefin–metal complexes or for carbonyl–metal‐ion interactions was obtained. The reactions did not proceed in the presence of the non‐coordinating base 2,6‐di‐tert‐butylpyridine. An excellent correlation of catalytic activities with cation hydrolysis constants was obtained. Different reactivities of mono‐ and dicarbonyl substrates have been rationalised. A 1H NMR probe for the assessment of proton generation was established and Lewis acids have been classified according to their propensity to hydrolyse in organic solvents. Brønsted acid‐catalysed conjugate addition reactions of nitrogen, oxygen, sulfur and carbon nucleophiles are developed and implications for asymmetric Lewis acid catalysis are discussed. 相似文献
6.
A novel synthetic route for LiFePO_4/C cathode materials by addition of starch for lithium-ion batteries 总被引:1,自引:0,他引:1
Shao Hua Luo Zi Long Tang Jun Biao Lu Zhong Tai Zhang State Key Laboratory of New Ceramics Fine Processing Department of Materials Science Engineering Tsinghua University Beijing China Graduate School at Shenzhen Tsinghua University Shenzhen China 《中国化学快报》2007,18(2):237-240
LiFePO4/Carbon composite cathode material was prepared using starch as carbon source by spray-pelleting and subsequent pyrolysis in N2. The samples were characterized by XRD, SEM, Raman, and their electrochemical performance was investigated in terms of cycling behavior. There has a special micro-morphology via the process, which is favorable to electrochemical properties. The discharge capacity of the LiFePO4.C composite was 170 mAh g-1, equal to the theoretical specific capacity at 0.1 C rate. At 4 C current density, the specific capacity was about 80 mAh g-1, which can satisfy for transportation applications if having a more flat discharge flat. 相似文献
7.
8.
9.
10.
Facile fabrication of porous NiO films for lithium-ion batteries with high reversibility and rate capability 总被引:1,自引:0,他引:1
We report the high-rate capability and good cyclability of three-dimension nanoporous NiO films as the anodes of lithium-ion
batteries. The NiO films are fabricated by immersing foam nickel substrates in an 80 °C aqueous solution containing ammonia
and potassium peroxydisulfate, and subsequent heat treatment at 500 °C. At a rate of 1.0 C, the film electrodes maintain a
capacity of 560 mAh g−1 as well as capacity retention of 97% after 100 discharge/charge cycles. When the current density is increased to 14C, 42%
of the capacity can be retained. Owing to the ease of large-scale fabrication and superior electrochemical performance, these
NiO films will be promising anodes for high-energy-density lithium-ion batteries. 相似文献
11.
Kawahara S Tsuzuki S Uchimaru T 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(15):4458-4464
Molecular interactions between pi systems having different pi-electron character (benzene, hexafluorobenzene, and borazine), and a Lewis acid/base (borane and ammonia) were theoretically studied. An attractive interaction between benzene, the electron-rich pi system, and borane was observed. On the other hand, repulsive interactions between benzene and ammonia was observed when the lone pair of nitrogen points toward the benzene ring. In contrast, an attractive interaction between hexafluorobenzene, an electron-deficient pi system, and ammonia was observed. Unexpectedly, a weak attractive interaction between hexafluorobenzene and borane was also observed. Borazine shows an interaction both to borane and ammonia. The attraction between the nitrogen atom of borazine and borane was larger than that between the boron atom of borazine and ammonia. 相似文献
12.
13.
14.
FANG LiSong ZHANG Qiao DENG ChunLin LEI XinSheng & LIN GuoQiang School of Pharmacy Fudan University Shanghai China Institutes of Biomedical Sciences Shanghai China 《中国科学B辑(英文版)》2011,(7)
Novel C-17-chloro-substituted derivative of vinorelbine or vinflunine has been regio-selectively synthesized via the chlorination reaction in the presence of Lewis acid.The catalyst Cp2TiCl2 plays a key role in the chlorination reaction. 相似文献
15.
16.
17.
18.
A classical Lewis adduct derives from a covalent bond between a Lewis acid and a base. When the adduct formation is precluded by means of steric hindrance the association of the respective acid-base molecular system is defined as a frustrated Lewis pair (FLP). In this work, the archetypal FLP Mes3P/B(C6F5)3 was characterized for the first time by resonance Raman spectroscopy, and the results were supported by density functional theory (DFT) calculations. The charge transfer nature of the lowest energy electronic transition, from phosphine to borane, was confirmed by the selective enhancement of the Raman bands associated to the FLP chromophore at resonance condition. Herein, we demonstrate the use of resonance Raman spectroscopy as a distinguished technique to probe the weak interaction involved in FLP chemistry. 相似文献
19.
20.
A three-component reaction of aromatic aldehydes, acetonitrile, and 2-thiohydantoins promoted by TiCl4 was discovered, and a different N-C-N bond-forming reaction took place with FeCl3, AlCl3 or BF3·Et2O as promoter. The thiohydantoin derivatives 1 and 3 were synthesized in moderate to high yields. A plausible mechanism for the formation of 1 and 3 is suggested. 相似文献