Li4Ti2.5Cr2.5O12 as anode material for lithium battery

Chromium-substituted Li₄Ti₅O₁₂ has been investigated as a negative electrode for future lithium batteries. It has been synthesized by a solid-state method followed by quenching leading to a micron-sized material. The minimum formation temperature of Li₄Ti_2.5Cr_2.5O₁₂ was found to be around 600 °C using thermogravimetric and differential thermal analysis. X-ray diffraction, scanning electron microscopy, cyclic voltammetry (CV), impedance spectroscopy, and charge–discharge cycling were used to evaluate the synthesized Li₄Ti_2.5Cr_2.5O₁₂. The particle size of the powder was around 2–4 μm. CV studies reveal a shift in the deintercalation potential by about 40 mV, i.e., from 1.54 V for Li₄Ti₅O₁₂ to 1.5 V for Li₄Ti_2.5Cr_2.5O₁₂. High-rate cyclability was exhibited by Li₄Ti_2.5Cr_2.5O₁₂ (up to 5  C) compared to the parent compound. The conduction mechanism of the compound was examined in terms of the dielectric constant and dissipation factor. The relaxation time has been evaluated and was found to be 0.07 ms. The mobility was found to be 5.133 × 10⁻⁶ cm² V⁻¹ s⁻¹.     

Synthesis and characterization of Co-doped lithium manganese oxide as a cathode material for rechargeable Li-ion battery

An attempt has been made to prepare cobalt-doped lithium manganese oxide with three different concentrations by simple molten salt method to enhance the electrical property of Li₄Mn₅O₁₂. Prepared samples were examined by XRD and SEM to identify its structure and morphology. Electrical properties were identified by impedance and conductivity analysis, and it was found that the material exhibits negative temperature coefficient (NTCR) property, i.e., semi-conducting nature. Among the various concentrations, 0.5 mol of Co-doped lithium manganese oxide has shown good conductivity of 3.1 × 10^?5 S cm^?1 at 433 K.     

锂离子电池SnSb/MCMB核壳结构负极材料嵌锂性能研究

以酸处理的中间相碳微球(MCMB)为载体, 用化学还原法在碳球表面沉积SnSb合金, 合成SnSb 包覆碳球的核壳结构负极材料. 采用XRD, SEM技术对材料的结构和形貌进行了表征, 用恒电流充放电(CC)、循环伏安(CV)和交流阻抗(EIS)测试了材料的电化学性能. 实验结果表明: SnSb/MCMB样品呈现纳米晶与非晶态的混合组织; 单一SnSb合金的容量衰减较快, 而对于SnSb/MCMB复合材料, 细小的合金颗粒均匀钉扎在MCMB表面, 不仅改善了颗粒的团聚现象, 而且增强了材料的导电能力, 使材料的循环稳定性得到改善, 复合材料具有936.161 mAh/g的首次放电比容量, 首次库仑效率80.3%, 50次循环后容量维持在498.221 mAh/g. 关键词： SnSb合金 锂离子电池 中间相碳微球(MCMB) 电化学性能     

Performance of developed natural vein graphite as the anode material of rechargeable lithium ion batteries

Electrochemical performance of natural vein graphite as an anode material for the rechargeable Li-ion battery (LIB) was investigated in this study. Natural graphite exhibits many favorable characteristics such as, high reversible capacity, appropriate potential profile, and comparatively low cost, to be an anode material for the LIB. Among the natural graphite varieties, the vein graphite typically possesses very high crystallinity together with extensively high natural purity, which in turn reduces the cost for purification. The developed natural vein graphite variety used for this study, possessed extra high purity with modified surface characteristics. Half-cell testing was carried out using CR 2032 coin cells with natural vein graphite as the active material and 1 M LiPF₆ (EC: DMC; vol. 1:1) as the electrolyte. Galvanostatic charge–discharge, cyclic voltammetry, and impedance analysis revealed a high and stable reversible capacity of 378 mA h g^?1, which is higher than the theoretical capacity (372 mA h g^?1 for LiC₆). Further, the observed low irreversible capacity acquiesces to the high columbic efficiency of over 99.9%. Therefore, this highly crystalline developed natural vein graphite can be presented as a readily usable low-cost anode material for Li-ion rechargeable batteries.     

Microwave-assisted synthesis of Cu2ZnSnS4 nanocrystals as a novel anode material for lithium ion battery

One-dimensional ordered quantum-ring chains are fabricated on a quantum-dot superlattice template by molecular beam epitaxy. The quantum-dot superlattice template is prepared by stacking multiple quantum-dot layers and quantum-ring chains are formed by partially capping quantum dots. Partially capping InAs quantum dots with a thin layer of GaAs introduces a morphological change from quantum dots to quantum rings. The lateral ordering is introduced by engineering the strain field of a multi-layer InGaAs quantum-dot superlattice.     

Hydrothermal synthesis of spinel Li1+x Mn2O4 as cathode material for rechargeable lithium battery

Abstract

The hydrothermal synthesis of Li-Mn spinel oxide (Li_1+xMn₂O₄) was undertaken in order to develop high quality, low cost cathode material for a rechargeable lithium battery. In our experiments, γ-MnOOH, LiOH · H₂O and H₂O₂ were used as starting materials to synthesize Li-Mn spinel oxide under hydrothermal conditions of 180-230°C and about 1.0-2.8 MPa. The chemical composition and particle size of the Li_1+xMn₂O₄ is easily controlled in the hydrothermal reaction. The Li_1+xMn₂O₄ produced was characterized by X-ray diffraction, with the spinel phase having a Li/Mn ratio of 0.50-0.60. There is convincing evidence, as a result of this work, that our synthesis process is most suitable for producing high quality cathode material that can be used in a rechargeable lithium battery.     

Mesoporous carbon-titania nanocomposites for high-power Li-ion battery anode material

We have investigated the Li-ion battery anode properties of several kinds of mesoporous composites of carbon and titanium dioxides (titania, TiO₂) prepared by tri-constituent co-assembly method. The maximum reversible capacity (197 mAh/g) at current density of 50 mA/g was obtained for the composite of TiO₂:carbon=7:3 calcined at 600 °C. It was also found that the composite maintained the high reversible capacity as large as 109 mAh/g even at the high current density of 1000 mA/g.     

Inorganic polymer phosphazene disulfide as cathode material for rechargeable lithium batteries

Novel inorganic network polymer phosphazene disulfide [(NPS₂)₃]_n was synthesized by a solution cross-link method. IR and element content analysis confirmed the polymer's molecular structure. The polymer has an average particle size of d_0.5 = 7.7 μm and the specific surface area is 57.4 m² g^− 1. TG/DTA analysis showed that [(NPS₂)₃]_n underwent a decomposition reaction from 200 to 300 °C. When used as cathode material in lithium batteries, its initial discharge capacity was 459.1 mAh g^− 1, which is almost 93.5% of theoretical specific capacity (490.9 mAh g^− 1). After 30 charge–discharge cycles, the discharge capacity of [(NPS₂)₃]_n stabilized at approximately 400.1 mAh g^− 1 which revealed an excellent cyclic ability. Therefore [(NPS₂)₃]_n is of great potential as cathode material for secondary lithium batteries.     

锂离子电池SnSb/C复合负极材料的热碳还原法制备及电化学性能研究

采用高温还原技术,以SnO2,SbO3为原料,分别以葡萄糖、中间相碳微球(MCMB)作为还原剂,制备了两种结构的SnSb/C复合材料,并对比了它们的形貌和电化学性能.采用X射线衍射技术、拉曼技术、扫描电子显微镜技术对材料的结构和形貌进行了表征,并且通过测试恒电流充放电曲线、循环伏安曲线和交流阻抗谱分析了材料的电化学性能.实验结果表明:葡萄糖作为还原剂时,形成以合金颗粒为内核,絮状碳壳均匀包裹的微米球状结构,首次放电比容量为793.379 mA·h·g-1,循环50周后仍维持在449.987 mA·h·g-1;而以MCMB作为还原剂时,形成合金颗粒与MCMB混合共存并部分包覆的结构,首次放电比容量为1164.938 mA·h·g-1,50周后的比容量仅有290.807 mA·h·g-1.     

Structural and electrical studies of LiMnVO4 cathode material for rechargeable lithium batteries

The lithium manganese vanadate (LiMnVO₄) cathode material was synthesized by using sol?Cgel method. The thermal behavior of the material has been examined by thermogravimetric and differential thermal analysis. The structure of LiMnVO₄ compound was studied by the Rietveld refined X-ray diffraction technique. Raman spectra showed that the local environment including VO₄ tetrahedra and LiO₆ octahedra as vibrational local units. X-ray photoelectron spectroscopy studies of synthesized LiMnVO₄ powder indicate that the oxidation states of manganese and vanadate are +2 and +5, respectively. The ionic conductivity of the sample is found to be 2.7?×?10^?5 Scm^?1 at 300?°C. The temperature dependent conductivity was conformed from the Arrhenius relation and the activation energy is found to be 0.3?eV. Dielectric spectra showed the decrease in dielectric constant with increase in frequency. Dielectric loss spectra reveal that dc conduction contribution predominates in the compound.     

锂离子电池负极材料CuSn的Li嵌入性质的研究

使用基于混合基表示的第一原理赝势法，研究了锂离子电池非碳类负极材料CuSn的Li嵌入时的形成能以及相应的电子结构.还给出了Li嵌入时的体积变化，能带结构、电子态密度以及电荷密度分布等性质, 并讨论了CuSn作为负极材料的特点.计算发现，Cu-Sn化合物在闪锌矿结构时，Li嵌入主体材料时的嵌入形成能大致在3.5eV附近. 关键词： 锂离子电池 负极材料 CuSn 电子结构     

First principles study on Mn-doped LiFePO4 as cathode material for rechargeable lithium batteries

The electronic structure and diffusion energy barriers of Li ions in pure and Mn-doped LiFePO4 have been studied using density functional theory （DFT）. The results demonstrate clearly that Fe - O covalent bond is weaker than P- O covalent bond. Pure LiFePO4 has band gap of 0.56 eV and diffusion energy barrier of 2.57 eV for Li ions, while the dopant has small band gap of 0.25 eV and low diffusion energy barrier of 2.31 eV, which indicates that the electronic and ionic conductivity of LiFePO4 have been improved owing to doping.     

Sn(II)-Treated MoO3 as cathode material for rechargeable lithium batteries

We report on the synthesis and structural, thermal and electrochemical characterisation of reduced molybdenum oxides with layered α-MoO₃ type structure. The samples have been prepared by reactions of various amounts of water-free tin dichloride with fine-particulated orthorhombic molybdenum trioxide in n-hexane (non-aqueous media) or in aqueous media, which yielded materials with different Sn:Mo ratio. XRD investigations of these materials proved that the crystal structure of the layered α-MoO₃ has been maintained after the reduction process. No crystalline impurity phases (e.g. tin oxides) could be detected by XRD. The tin-reduced samples exhibited a drastically improved cycling stability and capacity retention on cycling in 1 M LiClO₄/propylene carbonate, i.e. the discharge capacities were well above 100 mAh g⁻¹ after 20 cycles whereas the non-treated MoO₃ (reference sample) has retained only about 45 mAh g⁻¹. At higher cycle numbers (approx. cycle 100) the discharge capacity of the reduced molybdenum oxides stabilises at a level of approx. 100 mAh g⁻¹. This significant improvement of the rechargeability may be related to improved electronic conductivity and/or higher structural stabilisation of the layered MoO₃ structure either due to (i) a coating of the MoO₃ particles with a protective thin layer of a tin containing compounds, and/or (ii) an amorphisation of the structure after reductive treatment. Further efforts of this study were devoted to a variation of the conductive carbon content in the electrode composition and to changes of cut-off voltages and current densities. Paper presented at the 8th EuroConference on Ionics, Carvoeiro, Algarve, Portugal, Sept. 16–22, 2001.     

Synthesis and structure refinement studies of LiNiVO4 electrode material for lithium rechargeable batteries

The lithium nickel vanadate (LiNiVO₄) cathode material has been synthesized by using sol-gel method. The thermal behavior of the material has been examined by thermogravimetric and differential thermal analysis (TG/DTA). The structure of LiNiVO₄ compound has been studied by the Rietveld refined x-ray diffraction (XRD) technique. The Brunauer–Emmett–Teller (BET) surface area of 0.79 m² g^?1 was estimated with N₂ absorption characteristics. The synthesized powder morphology was observed by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). X-ray photoelectron spectroscopy (XPS) studies of synthesized LiNiVO₄ powder indicate that the oxidation states of nickel and vanadate are +2 and +5, respectively. The electrochemical properties were monitored using 2032 coin cells by cyclic voltammetry and EIS, which showed that the microscopic structural features were deeply related with the electrochemical performance.     

First principles study on Mn-doped LiFePO4 as cathode material for rechargeable lithium batteries

The electronic structure and diffusion energy barriers of Li ions in pure and Mn-doped LiFePO4 have been studied using density functional theory(DFT).The results demonstrate clearly that Fe-O covalent bond is weaker than P-O covalent bond.Pure LiFePO4 has band gap of 0.56 eV and diffusion energy barrier of 2.57 eV for Li ions,while the dopant has small band gap of 0.25 eV and low diffusion energy barrier of 2.31 eV,which indicates that the electronic and ionic conductivity of LiFePO4 have been improved owing to doping.     

锂离子电池Sn-Ti合金负极材料的制备及性能研究

采用磁控溅射沉积技术制备了纳米级Sn-Ti合金负极材料,并用X射线衍射和扫描电子显微镜进行表征,用高精度电池测试系统进行充放电和循环伏安测试.结果表明先镀Sn后镀Ti（Sn/Ti复合膜）和先镀Ti后镀Sn（Ti/Sn复合膜）具有很大的性能差异,其中Sn/Ti复合膜具有优异的循环稳定性和较高的可逆容量.首次放电容量和充电容量分别为9275 mAh/g和6954 mAh/g,首次库仑效率为75％,经30次循环后,该电极的放电容量保持为4152 mAh/g,这主要归因于活性物质Sn与电解液界面之间存在非活 关键词： 锂离子电池 磁控溅射 Sn-Ti合金 电化学性能     

Influence of post-calcination treatment on the spinel lithium titanium oxide anode material for lithium ion batteries

The influence of post-calcination treatment on spinel Li₄Ti₅O₁₂ anode material is extensively studied combining with a ball-milling-assisted rheological phase reaction method. The post-calcinated Li₄Ti₅O₁₂ shows a well distribution with expanded gaps between particles, which are beneficial for lithium ion mobility. Electrochemical results exhibit that the post-calcinated Li₄Ti₅O₁₂ delivers an improved specific capacity and rate capability. A high discharge capacity of 172.9 mAh g^?1 and a reversible charge capacity of 171.1 mAh g^?1 can be achieved at 1 C rate, which are very close to its theoretical capacity (175 mAh g^?1). Even at the rate of 20 C, the post-calcinated Li₄Ti₅O₁₂ still delivers a quite high charge capacity of 124.5 mAh g^?1 after 50 cycles, which is much improved over that (43.9 mAh g^?1) of the pure Li₄Ti₅O₁₂ without post-calcination treatment. This excellent electrochemical performance should be ascribed to the post-calcination process, which can greatly improve the lithium ion diffusion coefficient and further enhance the electrochemical kinetics significantly.     

Tamarind seed skin-derived fiber-like carbon nanostructures as novel anode material for lithium-ion battery

Demand of low-cost carbonaceous anode materials for lithium-ion batteries has led to the development of anode materials from different bio-sources. In this regard, tamarind seed (skin) was used as a precursor to prepare disordered carbon as an anode material for lithium-ion batteries. The carbon was prepared through simple hydrothermal method and was characterized by X-ray diffraction (XRD), Raman spectroscopy, Brunauer–Emmett–Teller (BET) measurements, field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM) techniques. It exhibited amorphous carbon particles arranged in a fiber-like morphology with high surface area of 508 m² g^?1. The binder content was optimized for the carbon to achieve high and stable capacity. Electrochemical performance of the as-prepared carbon with optimized binder content showed a stable reversible specific capacity of 224 mAhg^?1 after 300 cycles at 1 C-rate. The stable cycling performance of carbon at high current rate is explained by electrochemical impedance spectroscopy (EIS) and FE-SEM data of cycled electrodes. The low cost and stable specific capacity make the carbon as potential anode material for lithium-ion battery.

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Graphical abstract Fiber-like carbon nanostructures from tamarind seed (skin) (TDC) via simple and effective hydrothermal method and its application as a novel anode material for lithium-ion battery.

     

Effects of nitrogen on the carbon anode of a lithium secondary battery

Nitrogen-containing carbons have been made from different polymer precursors at 600°C. Their composition and structure have been studied by chemical analysis, X-ray powder diffraction and X-ray photoelectron spectroscopy. These results show that this kind of carbon is disordered, and nitrogen exists as two kinds of forms in the polymeric carbons: graphene nitrogen (N_1s binding energy 398.5 eV) and conjugated nitrogen (N_1s binding energy 400.2 eV). The discharge and charge process suggests that these two kinds of nitrogen are bonded satisfactorily and could not result in irreversible reaction with Li. The increase of reversible capacity mainly results from the graphene nitrogen, and the higher the content of nitrogen, the higher the charge capacity. Part of the irreversible capacity is derived from the formed lithium carbide and lithium atoms which are intercalated and could not be deintercalated.     

Synthesis and characterization of Cr8O21 as cathode material for rechargeable lithium batteries

Pure phase Cr₈O₂₁ with excellent electrochemical properties has been synthesized by sintering anhydrous chromium trioxide (CrO₃) at low temperature in flowing oxygen. Cyclic voltammetry (CV) and X-ray diffraction (XRD) characterizations indicate that the inner tetra-chromate groups of Cr₈O₂₁ are damaged and Cr₈O₂₁ is changed to another layer-structured material when lithium is inserted into the host.