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131.
Dr. Lars Borchardt Dr. Martin Oschatz Prof. Dr. Stefan Kaskel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(22):7324-7351
Lithium–sulfur batteries are among the most promising electrochemical energy storage devices of the near future. Especially the low price and abundant availability of sulfur as the cathode material and the high theoretical capacity in comparison to state‐of‐the art lithium‐ion technologies are attractive features. Despite significant research achievements that have been made over the last years, fundamental (electro‐) chemical questions still remain unanswered. This review addresses ten crucial questions associated with lithium–sulfur batteries and critically evaluates current research with respect to them. The sulfur–carbon composite cathode is a particular focus, but its complex interplay with other hardware components in the cell, such as the electrolyte and the anode, necessitates a critical discussion of other cell components. Modern in situ characterisation methods are ideally suited to illuminate the role of each component. This article does not pretend to summarise all recently published data, but instead is a critical overview over lithium–sulfur batteries based on recent research findings. 相似文献
132.
Chemically shortened multi-walled carbon nanotubes used as anode materials for lithium-ion batteries
An easy chemically cutting process, modified Hummers' method, was proposed to treat multi-walled carbon nanotubes, successfully cutting pristine long, entangled carbon nanotubes into hydrosoluble pieces, mostly less than 200 nm. This short, chemically oxidized carbon nanotube was then applied as an anode material for lithium-ion batteries. The as-prepared material possessed higher reversible capacity and coulombic efficiency. The intrinsic factors were explored by X-ray photoelectron spectroscopy and cyclic voltammetry. 相似文献
133.
134.
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
135.
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
136.
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
137.
Dr. Zhiyu Wang Zi Chen Wang Prof. Srinivasan Madhavi Prof. Xiong Wen Lou 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(24):7561-7567
A versatile one‐step method for the general synthesis of metal oxide hollow nanostructures is demonstrated. This method involves the controlled deposition of metal oxides on shaped α‐Fe2O3 crystals which are simultaneously dissolved. A variety of uniform SnO2 hollow nanostructures, such as nanococoons, nanoboxes, hollow nanorings, and nanospheres, can be readily generated. The method is also applicable to the synthesis of shaped TiO2 hollow nanostructures. As a demonstration of the potential applications of these hollow nanostructures, the lithium storage capability of SnO2 hollow structures is investigated. The results show that such derived SnO2 hollow structures exhibit stable capacity retention of 600–700 mAh g?1 for 50 cycles at a 0.2 C rate and good rate capability at 0.5–1 C, perhaps benefiting from the unique structural characteristics. 相似文献
138.
Germanium Quantum Dots Embedded in N‐Doping Graphene Matrix with Sponge‐Like Architecture for Enhanced Performance in Lithium‐Ion Batteries 下载免费PDF全文
Jinwen Qin Xia Wang Prof. Dr. Minhua Cao Changwen Hu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(31):9675-9682
Germanium quantum dots embedded in a nitrogen‐doped graphene matrix with a sponge‐like architecture (Ge/GN sponge) are prepared through a simple and scalable synthetic method, involving freeze drying to obtain the Ge(OH)4/graphene oxide (GO) precursor and subsequent heat reduction treatment. Upon application as an anode for the lithium‐ion battery (LIB), the Ge/GN sponge exhibits a high discharge capacity compared with previously reported N‐doped graphene. The electrode with the as‐synthesized Ge/GN sponge can deliver a capacity of 1258 mAh g?1 even after 50 charge/discharge cycles. This improved electrochemical performance can be attributed to the pore memory effect and highly conductive N‐doping GN matrix from the unique sponge‐like structure. 相似文献
139.
Yongjin Fang Deyan Luan Ye Chen Shuyan Gao Xiong Wen Lou 《Angewandte Chemie (International ed. in English)》2020,59(18):7178-7183
Hybrid materials, integrating the merits of individual components, are ideal structures for efficient sodium storage. However, the construction of hybrid structures with decent physical/electrochemical properties is still challenging. Now, the elaborate design and synthesis of hierarchical nanoboxes composed of three‐layered Cu2S@carbon@MoS2 as anode materials for sodium‐ion batteries is reported. Through a facile multistep template‐engaged strategy, ultrathin MoS2 nanosheets are grown on nitrogen‐doped carbon‐coated Cu2S nanoboxes to realize the Cu2S@carbon@MoS2 configuration. The design shortens the diffusion path of electrons/Na+ ions, accommodates the volume change of electrodes during cycling, enhances the electric conductivity of the hybrids, and offers abundant active sites for sodium uptake. By virtue of these advantages, these three‐layered Cu2S@carbon@MoS2 hierarchical nanoboxes show excellent electrochemical properties in terms of decent rate capability and stable cycle life. 相似文献
140.
Biwei Xiao Hanshuo Liu Ning Chen Mohammad Norouzi Banis Haijun Yu Jianwen Liang Qian Sun Tsun‐Kong Sham Ruying Li Mei Cai Gianluigi A. Botton Xueliang Sun 《Angewandte Chemie (International ed. in English)》2020,59(34):14313-14320
Li‐ and Mn‐rich layered oxides are among the most promising cathode materials for Li‐ion batteries with high theoretical energy density. Its practical application is, however, hampered by the capacity and voltage fade after long cycling. Herein, a finite difference method for near‐edge structure (FDMNES) code was combined with in situ X‐ray absorption spectroscopy (XAS) and transmission electron microscopy/electron energy loss spectroscopy (TEM/EELS) to investigate the evolution of transition metals (TMs) in fresh and heavily cycled electrodes. Theoretical modeling reveals a recurring partially reversible LiMn2O4‐like sub‐nanodomain formation/dissolution process during each charge/discharge, which accumulates gradually and accounts for the Mn phase transition. From the modeling of spectra and maps of the valence state over large regions of the cathodes, it was found that the phase change is size‐dependent. After prolonged cycling, the TMs displayed different levels of inactivity. 相似文献