LiCoO2中锂离子固相扩散系数随循环次数的变化

The solid diffusion coefficient of lithium-ion in LiCoO₂ cathode material has been investigated by the capacity intermittent titration technique (CITT) at different voltages and at different charge/discharge cycles. By SEM, XRD and FTIR techniques, the structure of LiCoO₂ was studied before and after charge-discharge cycles, and the relationship between solid diffusion coefficient and crystal structure was further discussed. CITT results show that the value of Li⁺ solid diffusion coefficient of LiCoO₂ is about 10^-12 cm²·s^-1. During the whole charge-discharge cycles, the Li⁺ solid diffusion coefficient decreased within the voltage of 4.0～4.3 V, which is attributed to the change of the structure of LiCoO₂.     

Donor-acceptor properties, catalytic activity, and negative charge exoemission from the alumina surface modified with lithium cations

Donor-acceptor properties of alumina modified with lithium cations were studied by ESR of paramagnetic complexes of adsorbed anthraquinone. The results were compared with the data on negative ion emission (exoemission) accompanying the decomposition of isopropyl alcohol in the adsorption layer. The data on the activity measured by the pulse microcatalytic technique in isopropyl alcohol decomposition are discussed. Small additives of lithium were found to promote catalytic activity of the samples. The role of acid and basic sites in isopropyl alcohol decomposition was discussed. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 616–621, April, 2006.     

熔融浸渍法制备锂离子电池正极材料LiMn2O4的研究

采用LiNO3和MnO2为原料,在650℃下制备了尖晶石型的LiMn2O4.通过X射线衍射、扫描电子显微镜、热重分析和电化学性能测试,发现该化合物具有很高的放电比容量和较好的循环性能,首次放电比容量可达到122 mA·h/g.并对循环性能衰减的各种因素进行了讨论.     

尖晶石锂锰氧化物锂离子嵌脱过程的交流阻抗谱研究

用粉末微电极研究了尖晶石锂锰氧化物在不同嵌锂状态下嵌脱锂过程的交流阻 抗图谱，提出了新的等效电路模型。描述锂离子在固体中扩散的Warburg阻抗与累 积或消耗的嵌入电容在Lix MnO4中的x≤0．5时串联，0．5＜x≤1时并联。用提出 的等效电路模型分阶段拟合了实验所得的交流阻抗谱，拟合值与实验值相当吻合， 由拟合结果得到不同电位下锂离子在表面膜中的迁移电阻和电容，界面电荷传递电 阻，双层电容，锂离子在固体中扩散系数和累积或消耗的嵌入电容。     

四元交互体系Li~＋，Mg~（2＋）／Cl~－，SO_4~（2－）－H_2O

本文采用等温溶解平衡法研究了四元交互体系Ｌｉ＋，Ｍｇ２＋／ＣＩ－，ＳＯ－Ｈ２Ｏ２５℃的机关系和平衡液相的物化性质（密度、粘度、电导率、折光率和ｐＨ）．该体系２５℃有七个相区Ｌｉ２ＳＯ４·Ｈ２Ｏ，ＭｇＳＯ４·７Ｈ２Ｏ．ＭｇＳＯ４·６Ｈ２Ｏ．ＭｇＳＯ４·５Ｈ２Ｏ，ＭｇＣ１２，６Ｈ２Ｏ，ＬｉＣＩ．ＭｇＣｌ２．７Ｈ２Ｏ，ＬｉＣＩ·Ｈ２Ｏ，十一条单变量线，五个共饱点．其中ＬｉＣＩ·Ｈ２Ｏ＋ＬｉＣＩ·ＭｇＣｌ２·７Ｈ２Ｏ＋Ｌｉ２ＳＯ４·Ｈ２Ｏ为一致零变量点．与文献中的研究结果比较，我们得到两个新相区ＭｇＳＯ４·６Ｈ２Ｏ和ＭｇＳＯ４·５Ｈ２Ｏ．用经验和半经验公式计算了平衡液相的密度、折光率．由实验测定的溶解度数据求得了高锂浓度下的Ｐｉｔｚｅｒ参数．对该体系２５℃溶解度进行了理论计算复证．     

Nontrivial structural organization of pivalate complexes with the fragment {Fe2Li(μ3-O)}

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Structural and electrochemical studies of annealed LiNiVO4 thin films

We prepared stoichiometric lithium nickel vanadate amorphous thin films by using r.f. magnetron sputtering under controlled oxygen partial pressure. The amorphous films were heated at various temperatures, 300–600 °C, for 8 h. The as‐deposited and annealed thin films were characterized by Rutherford backscattering spectroscopy, nuclear reaction analysis, Auger electron spectroscopy, X‐ray diffraction, scanning electron microscopy and atomic force microscopy. The electrochemical behavior of the various films was studied by the galvanostatic method. The cells were tested in a liquid electrolyte at room temperature, with lithium metal used as the counter and reference electrode. The best electrochemical storage value was obtained with the thin film annealed at 300 °C, which showed superior capacity and small capacity loss during cycling. Copyright © 2007 John Wiley & Sons, Ltd.     

单斜层状LiMnO2的球磨-离子交换法合成及其电化学性能研究

通过球磨促进固相反应法合成出了具有单斜层状结构的前驱物NaMnO₂，随后通过离子交换得到了单斜层状LiMnO₂。XRD测试结果显示产物为单相。扫描电镜(SEM)和透射电镜(TEM)观测结果显示LiMnO₂的粒子尺寸为300～500 nm，HRTEM分析显示干扰条纹的间距为0.485 nm，基本对应于m-LiMnO₂的(001)晶面间距。红外吸收光谱(IR)和X射线光电子能谱(XPS)被用来测量m-LiMnO₂中Mn-O键的伸缩和弯曲振动吸收和Mn元素的价态。合成的m-LiMnO₂在电化学充放电循环初期表现了较好的电化学性能，但其循环寿命仍需要进一步改善。     

微乳液法合成LiFePO4 / C正极材料及其电化学性能

本文采用微乳液方法合成了纳米LiFePO₄ / C正极材料。制备样品分别用XRD和SEM进行表征，充放电测试其电化学性能。600 ℃制备样品为单一物相，平均粒径90 nm，在室温2.0～4.0 V (vs Li) 放电电压范围和15 mA·g^-1放电速率下，首次放电容量达到159 mAh·g^-1。制备样品同样展现良好的循环性能。在15 mA·g^-1速率下40次循环后，制备样品放电容量仍保持首次放电容量的98.9%。优异的电化学性能得益于样品颗粒的纳米尺寸、均匀分布以及表面碳层包覆提高了活性材料的电子电导率。