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41.
A Microporous Covalent–Organic Framework with Abundant Accessible Carbonyl Groups for Lithium‐Ion Batteries 下载免费PDF全文
Zhiqiang Luo Luojia Liu Jiaxin Ning Kaixiang Lei Yong Lu Prof. Fujun Li Prof. Jun Chen 《Angewandte Chemie (International ed. in English)》2018,57(30):9443-9446
A key challenge faced by organic electrodes is how to promote the redox reactions of functional groups to achieve high specific capacity and rate performance. Here, we report a two‐dimensional (2D) microporous covalent–organic framework (COF), poly(imide‐benzoquinone), via in situ polymerization on graphene (PIBN‐G) to function as a cathode material for lithium‐ion batteries (LIBs). Such a structure favors charge transfer from graphene to PIBN and full access of both electrons and Li+ ions to the abundant redox‐active carbonyl groups, which are essential for battery reactions. This enables large reversible specific capacities of 271.0 and 193.1 mAh g?1 at 0.1 and 10 C, respectively, and retention of more than 86 % after 300 cycles. The discharging/charging process successively involves 8 Li+ and 2 Li+ in the carbonyl groups of the respective imide and quinone groups. The structural merits of PIBN‐G will trigger more investigations into the designable and versatile COFs for electrochemistry. 相似文献
42.
Nano-crystalline FeOOH particles(5~10 nm) have been uniformly mixed with electric matrix of single-walled carbon nanotubes(SWNTs)for forming FeOOH/SWNT composite via a facile ultrasonication method. Directly using the FeOOH/SWNT composite(containing 15 wt%SWNTs) as anode material for lithium battery enhances kinetics of the Li+insertion/extraction processes, thereby effectively improving reversible capacity and cycle performance, which delivers a high reversible capacity of 758 mAh g-1under a current density of 400 mA g-1even after 180 cycles, being comparable with previous reports in terms of electrochemical performance for FeOOH anode. The good electrochemical performance should be ascribed to the small particle size and nano-crystalline of FeOOH, as well as the good electronic conductivity of SWNT matrix. 相似文献
43.
Synthesis of Single‐Crystalline Spinel LiMn2O4 Nanorods for Lithium‐Ion Batteries with High Rate Capability and Long Cycle Life 下载免费PDF全文
Xiuqiang Xie Dr. Dawei Su Dr. Bing Sun Jinqiang Zhang Prof. Dr. Chengyin Wang Prof. Dr. Guoxiu Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(51):17125-17131
The long‐standing challenge associated with capacity fading of spinel LiMn2O4 cathode material for lithium‐ion batteries is investigated. Single‐crystalline spinel LiMn2O4 nanorods were successfully synthesized by a template‐engaged method. Porous Mn3O4 nanorods were used as self‐sacrificial templates, into which LiOH was infiltrated by a vacuum‐assisted impregnation route. When used as cathode materials for lithium‐ion batteries, the spinel LiMn2O4 nanorods exhibited superior long cycle life owing to the one‐dimensional nanorod structure, single‐crystallinity, and Li‐rich effect. LiMn2O4 nanorods retained 95.6 % of the initial capacity after 1000 cycles at 3C rate. In particular, the nanorod morphology of the spinel LiMn2O4 was well‐preserved after a long‐term cycling, suggesting the ultrahigh structural stability of the single crystalline spinel LiMn2O4 nanorods. This result shows the promising applications of single‐crystalline spinel LiMn2O4 nanorods as cathode materials for lithium‐ion batteries with high rate capability and long cycle life. 相似文献
44.
《Progress in Solid State Chemistry》2014,42(4):191-201
Antimony containing compounds have drawn interest as anode materials in Li batteries due to their high Li packing density and the resulting volumetric charge density. Reasonable specific capacities outperforming graphite by a factor of 2 have been reported for antimonides and polyantimonides. Together with good cycling stabilities, rate capabilities and a high potential level against Li metal, both classes of materials are discussed as potential candidates to substitute carbonaceous hosts. Unfortunately, severe volume expansion during the reaction with lithium takes place which has to be taken into account during optimization of the systems. This feature demands size tailoring and electrode optimization to push the electrochemical performance and the lifetime of half cells and full batteries in applicable dimensions. While antimonides are more or less intermetallic compounds, performing a conversion reaction to electrochemical active (in most cases Sb) and non-active species, polyantimonides can offer a greater flexibility due to their anisotropic structural features. Polyantimonides, containing simple dumbbells up to layered arrangements of covalently bonded antimony, can provide voids or interstitials for insertion and intercalation of lithium. The chance to preserve such favourable structural features during this process is in principle higher than for antimonides where conversion reactions to other species take place.Herein we report on structural features and electrochemical performance of antimony containing active materials for anodes in lithium batteries. Our focus lies on recent developments in polyantimonides chemistry but we will also address the scientific progress with antimonides. 相似文献
45.
A simple method was proposed to prepare nanosized Si composite anode materials for lithium-ion (Li-ion) batteries. The preparation
started with the shock-type ball milling of silicon in liquid media of polyacrylonitrile (PAN)/dimethylformamide (DMF) solution,
forming slurry where the nano-Si particles were uniformly dispersed, followed by the drying of the slurry to remove DMF. The
nanosized Si composite anode material was obtained after the pyrolysis of the mixture at 300 °C where the pyrolyzed PAN provided
a conductive matrix to relieve the morphological change of Si during cycling. As-prepared composite presented good cyclability
for lithium storage. The proposed process paves an effective way to prepare high performance Si, Sn, Sb and their alloys based
composite anode materials for Li-ion batteries. 相似文献
46.
Nanoscopic scale studies of LiFePO4 as cathode material in lithium-ion batteries for HEV application
We present a review of the structural properties of LiFePO4. Depending on the mode of preparation, different impurities can poison this material. These impurities are identified and
a quantitative estimate of their concentrations is deduced from the combination of X-ray diffraction analysis, Fourier transform
infrared spectroscopy, Raman spectroscopy, and magnetic measurements. An optimized preparation provides samples with carbon-coated
particles free of any impurity phase, insuring structural stability and electrochemical performance that justify the use of
this material as a cathode element a new generation of lithium secondary batteries. 相似文献
47.
Surface morphology in 3.5 × 3.5 μm2 area of spinel LiMn2O4, which is a typical cathode material for Li ion secondary batteries, is studied using an atomic force microscopy (AFM) with a conductive probe. Negative bias voltage is applied to the probe to attract Li+ ions toward LiMn2O4 surface during the AFM observation. Before applying the voltage (0 V), the whole LiMn2O4 surface is covered with scale-shaped grains. Under the negative voltage of 5.5 V, electric current abruptly increases, indicating Li+ ionic conduction. Simultaneously, part of the scale-shaped grains expand and flatten. Jahn-Teller phase transition, which is induced by the repulsive interaction between the Mn-eg and O-2p electrons in Li accumulated layer, is proposed as a possible origin of these results. 相似文献
48.
49.
Organic electrode materials (OEMs) are being investigated as promising candidates for aqueous zinc-ion batteries (AZIBs) owing to their environmental friendliness, cost-effectiveness, and structural diversity, and tunability. Understanding the correlation between structural regulation of OEMs and their electrochemical property in AZIBs is vital to rational design of OEMs. Herein, we first discuss the fundamentals of the energy storage mechanism of OEMs. Then, strategies to improve the electrochemical performance, including the specific capacity, voltage, rate capability, and cycling stability, are elaborated from the perspective of molecular engineering. Finally, we share our views on the remaining challenges and prospects of OEMs in AZIBs. 相似文献
50.
Hong Guo Yapeng Wang Wei Wang Lixiang Liu Yuanyuan Guo Xiangjun Yang Shixiong Wang 《Particle & Particle Systems Characterization》2014,31(3):374-381
Hollow NiO–carbon hybrid nanoparticle aggregates are fabricated through an environmental template‐free solvothermal alcoholysis route. Controlled hollow structure is achieved by adjusting the ratio of ethylene glycol to water and reaction time of solvothermal alcoholysis. Amorphous carbon can be loaded on the NiO nanoparticles uniformly in the solvothermal alcoholysis process, and the subsequent calcination results in the formation of hollow NiO–C hybrid nanoparticle aggregates. As anode materials for lithium‐ion batteries, it exhibits a stable reversible capacity of 622 mAh g?1, and capacity retention keeps over 90.7% after 100 cycles at constant current density of 200 mA g?1. The NiO–C electrode also exhibits good rate capabilities. The unique hollow structures can shorten the length of Li‐ion diffusion and offer a sufficient void space, which sufficiently alleviates the mechanical stress caused by volume change. The hybrid carbon in the particles renders the electrode having a good electronic conductivity. Here, the hollow NiO‐C hybrid electrode exhibits excellent electrochemical performance. 相似文献