LiNi1-xMxO2 (M =Co3+, Al3+)的制备与性能

采用球形Ni(OH)2和LiNO3、CoO、Al(OH)3为原料，在空气气氛条件下700℃恒温8h，合成了锂离子电池正极材料LiNixCo1-xO2和LiNi0.75Al0.25O2。X射线衍射分析表明合成的材料粉末结晶良好，具有规整的α-NaFeO2层状结构；SEM分析表明粉末颗粒呈球形，粒径约为7μm。充放电测试表明：合成的LiNixCo1-xO2正极材料的充电比容量为160mAh／g，放电比容量为152mAh／g；LiNi0.75Al0.25O2正极材料的充电比容量为140mAh／g，放电比容量为129mAh／g；这两种正极材料具有优良的电化学性能。     

基于容量参数的二次电池嵌入型电极材料固相扩散系数的测定方法

介绍了一种以容量参数为主变量的测定锂二次电池中电极材料固相扩散系数的方法.该方法只需颗粒半径这一辅助参数,通过球型扩散模型建立了恒流-恒压充电容量(RPG)比,进一步发展成为容量间歇滴定技术(CITT).采用RPG法可在较宽的电压范围内测定嵌入型电极材料的平均固相扩散系数,实验结果重现性好.由RPG法测得0～1.5 V时锂离子在石墨电极中的平均固相扩散系数值为1.055×10-10cm2/s.由CITT技术测得锂离子在LiMn2 O4中的固相扩散系数在3.95 V和4.12 V左右存在个两个极小峰,且随着循环次数的增加,扩散系数值逐渐增大.     

Phase transition of lithiated-spinel Li2Mn2O4 at high temperature

1 Introduction Lithium manganese oxides are the most attractive cathode materials for rechargeable lithium-ion batteries because of their low-cost and less toxicity when compared with either cobaltates or nickelates[1?3]. Among these oxides, the spinel-fr…     

锂离子电池正极材料第一原理计算研究

利用第一原理计算方法可分析和预测锂-金属氧化物电池正极材料在Li离子嵌入脱出过程中的电势和稳定性等性能。本文详细介绍了第一原理计算方法的理论背景以及目前LiCoO2正极材料计算研究的现状。利用此方法对LiNiO2及多组分材料掺杂进行研究是今后工作的重点。     

Effect of annealing treatment on electrochemical property of LiNi0.5Mn1.5O4 spinel

LiNi0.5Mn1.5O4 was prepared under different cooling conditions. The electrochemical properties of LiNi0.5Mn1.5O4 prepared under different cooling conditions were investigated. The results show that LiNi0.5Mn1.5O4 synthesized with or without annealing treatment has similar X-ray diffraction patterns that can be indexed to cubic spinel structure. The mass loss occurring above 650℃ during the heating process can be mostly gained during the cooling process. LiNi0.5Mn1.5O4 synthesized with an annealing treatment exhibits almost one voltage plateau at around 4.7 V and higher capacity with a quick fading upon cycling, whereas LiNi0.5Mn1.5O4 synthesized without annealing treatment shows two voltage plateaus at around 4.1 and 4.7 V and superior capacity retention upon cycling both at rates of 1/7C and 1 C, though the capacity is not high.     

Synthesis and electrochemical properties of Th-doped LiMn2O4 powders for lithium-ion batteries

To improve the cycle performance of eco-friendly and cost-effective spinel LiMN2O4 as the Li secondary batteries, the Th-doped LiThxMn1-xO4 spinel powers were synthesized by solid-state method. The starting materials, Li2CO3,MnO2 and Th(NO3)4·4H2O, were mixed uniformly using a traditional ball milling, which resulted in a uniform particle size distribution in the mixed powers. Tests of X-ray diffraction, SEM, impedance spectra and charge-discharge were carried out for LiThxMn1-xO4 cathode materials. Results show that the synthesized LiTh0.01Mn1.99O4 material exhibits standard spinel structure, regular particle morphology and excellent property of charge-discharge for big current. The capacity retention of the material modified by doping Th is more than 85.1% of the first discharge specific capacity of 111.5 mAh·g -1 after 20 cycles at the current rate 1C, while the pristine LiMN2O4 is only 57% of the first discharge specific capacity of 110.2 mAh·g-1 after the same cycles at the same current rate.     

锂电极表面膜的组成和阻抗行为

介绍了锂电池中锂电极的表面膜的组成和阻抗行为，并根据其表面膜的阻抗行为提出了电化学模型。     

Effect of MoS2 morphology on the HDS activity of hydrotreating catalysts

We have applied near-edge X-ray absorption fine structure (NEXAFS) to characterize the surface and bulk properties of Li_xNi_1–xO catalysts. In our experimental set-up, NEXAFS spectra of powder materials could be obtained by measuring the intensity of either electron-yield or fluorescence-yield. While the electron-yield method is sensitive only to the top few atomic layers, the fluorescence-yield method can detect species up to a few thousands angstroms deep into the bulk structure. The ability to distinguish surface and bulk compositions is demonstrated in studies of a number of Li_0.5Ni_0.5O samples, of which the surface compositions vary as a function of preparation procedures. In addition, NEXAFS investigations following the reaction of Li_xNi_1–xO with CH₄ have also been carried out and the results indicate that the initial surface reaction intermediates are Li₂CO₃.     

R12TAB/正丁醇/正癸烷/水体系相态的研究

绘制了阳离子表面活性剂R12TAB／正丁醇／正癸烷／水体系的拟三元相图，确定了微乳液区、微乳液／液晶共存区及不同液晶区域的范围。用^2HNMR和差示扫描量热法(DSC)与液晶纹理相互对照，研究了该体系的液晶结构特点。结果表明：含质量分数为25％～75％正癸烷的各相图内，除了存在着层状、六角状单相液晶区和层状／六角状／立方状共存的混合液晶区域外，还存在着液晶／微乳液共存的区域，且随着正癸烷质量分数的增加，微乳液及液晶区域逐渐缩小。