Li/Li(100)面自扩散体系的理论研究

本文应用对势方法构造了Li/Li(100)表面缺陷体系的吸附扩散相互作用模型势,考察了各种台阶、扭结、空位等表面缺陷对锂原子表面吸附扩散行为的影响。根据缺陷表面体系结合能和表面扩散活化势垒的结果,提出和分析了捕获能力和捕获网链的概念。     

Self-assembled Li4Ti5O12/TiO2/Li3PO4 for integrated Li–ion microbatteries

This work aims to maximize the number of active sites for energy storage per geometric area, by approaching the investigation to 3D design for microelectrode arrays. Self-organized Li₄Ti₅O₁₂/TiO₂/Li₃PO₄ composite nanoforest layer (LTL) is obtained from a layer of self organized TiO₂/Li₃PO₄ nanotubes. The electrochemical response of this thin film electrode prepared at 700 °C exhibited lithium insertion and de-insertion at 1.55 and 1.57 V respectively, which is the typical potential found for lithium titanates. The effects of lithium phosphate on lithium titanate are explored for the first time. By cycling between 2.7 and 0.75 V the LTL/LiFePO₄ full cell delivered 145 mA h g^− 1 at an average potential of 1.85 V leading to an energy density of 260 W h kg^− 1 at C/2. Raman spectroscopy revealed that the γ-Li₃PO₄/lithium titanate structure is preserved after prolonged cycling. This means that Li₃PO₄ plays an important role for enhancing the electronic conductivity and lithium ion diffusion.     

快离子导体系统中Li+运动的7Li NMR研究

Lil＋2。TiZ。Mg。P3012是一种具有较高离子导电车的快离子导体材料，其结晶化学和电导性能都已经进行了深入的研究，表明化合物具有规整的三维骨架结构，h离子位于骨架间隙中，并且其离子电导率随温度升高而增加＊．作者曾应用”P固体高分辨NMR技术对该固港体系统的微观晶体结构进行了研究，分析了Mg’“离子部分替代Ti‘“离子后，化合物骨架结构的特征＊．但对该体系的Li离子微观动态行为的研究还没有开展，在这里我们应用、i固体NMR技术研究了L计的状态及其动态行为，在此基J由上分析了Li离子可能的迁移机理．1实验部分’LiNMR…     

Li3Al和Li2B2的稳定性和垂直激发态光谱

对于较大的簇合物，电子衍射技术或许能得到有用的信息[1].而小簇合物Mn（3≤n《50）的几何结构就没有标准的方法加以测定．对于二聚体和三聚体[2-5]，振动光谱和转动光谱能够得到精确的核间距和基态的势能面．当n》4时，若要得到一个有价值的结果，需要进行很复杂的振动结构分析．对于这类小簇合物只能得到它们的吸收光谱[6-7].因此，计算其垂直激发态就具有非常重要的意义．用量子化学解释簇合物的吸收光谱已成为一个非常诱人的课题[8].从头算对碱金属簇合物的垂直激发态计算，并与实验光谱进行比较，已成功地预测了一些碱金属簇合物的基…     

Li4Ti5Ol2的合成及对Li+的离子交换动力学

用溶胶-凝胶法合成出Li4Ti5Ol2, 对其进行了酸改性, 制得锂离子筛IE-H. 测定了IE-H对Li+、Na+的饱和交换容量和pH滴定曲线等离子交换性能, 并对其进行了X射线衍射分析, 同时采用中断接触法判断该离子交换反应的控制机理, 用缩核模型描述离子筛IE-H交换Li+的动力学. 结果表明, 合成出的Li4Ti5Ol2和锂离子筛IE-H均为尖晶石结构; 用不同浓度HNO3溶液处理Li4Ti5Ol2时, Li+的抽出率为19.6%-81.5%, Ti4+的抽出率在4.2%以下; 锂离子筛IE-H 对Li+的饱和交换容量较高, 达到5.95 mmol·g-1, 离子筛IE-H交换Li+的控制步骤是颗粒扩散控制(PDC), 得到了25 ℃, Li+浓度为20.0 mmol·L-1和5.0 mmol·L-1时锂离子筛交换Li+的动力学方程和颗粒扩散系数.     

Electrochemical Reactivation of Dead Li2S for Li−S Batteries in Non-Solvating Electrolytes

The use of non-solvating, or as-called sparingly-solvating, electrolytes (NSEs), is regarded as one of the most promising solutions to the obstacles to the practical applications of Li−S batteries. However, it remains a puzzle that long-life Li−S batteries have rarely, if not never, been reported with NSEs, despite their good compatibility with Li anode. Here, we find the capacity decay of Li−S batteries in NSEs is mainly due to the accumulation of the dead Li₂S at the cathode side, rather than the degradation of the anodes or electrolytes. Based on this understanding, we propose an electrochemical strategy to reactivate the accumulated Li₂S and revive the dead Li−S batteries in NSEs. With such a facile approach, Li−S batteries with significantly improved cycling stability and accelerated dynamics are achieved with diglyme-, acetonitrile- and 1,2-dimethoxyethane-based NSEs. Our finding may rebuild the confidence in exploiting non-solvating Li−S batteries with practical competitiveness.     

Li含量对Li/MgO丙烷氧化脱氢制烯烃反应催化性能的影响

采用浸渍法制备了不同Li含量的Li/MgO催化剂,并通过TG-DTA、N_2吸附及XRD等手段对其进行了表征;对丙烷在Li/MgO催化剂表面的两种吸附状态所占据的空间体积大小进行了计算,研究了Li含量对其丙烷氧化脱氢制烯烃反应催化性能的影响。结果表明,随着Li/MgO催化剂中Li含量的增加,丙烷转化率与乙烯、甲烷、乙烷和COx的选择性均先增加,在Li物质的量分数为3%时达到最高,然后随Li含量增加而降低,而丙烯选择性则出现相反的变化趋势。丙烷在Li/MgO催化剂上的吸附和反应同时受动力学和热力学两个因素的制约;Li负载量不同,反应活性位Li+O-分散状态也不同,导致产物分布发生变化。活性位分散度高时受热力学因素影响,有利于生成丙烯;活性位分散度低时受吸附动力学影响,更趋向于生成乙烯等其他产物。     

Electrochemical reactivity of Li–Mn–O and Li–Fe–Mn–O spinels

Electrochemical reductive dissolution of Li–Mn–O and Li–Fe–Mn–O spinels and Li⁺ extraction/insertion in these oxides were performed using voltammetry of microparticles. Both electrochemical reactions are sensitive to the Fe/(Fe+Mn) ratio, specific surface area, Li content in tetrahedral positions, and Mn valence, and can be used for electrochemical analysis of the homogeneity of the elemental and phase composition of synthetic samples. The peak potential (E _P) of the reductive dissolution of the Li–Mn–O spinel is directly proportional to the logarithm of the specific surface area. E _P of Li–Fe–Mn–O spinels is mainly controlled by the Fe/(Fe+Mn) ratio. Li⁺ insertion/extraction can be performed with Mn-rich Li–Fe–Mn–O spinels in aqueous solution under an ambient atmosphere and it is sensitive to the regularity of the spinel structure, in particularly to the amount of Li in tetrahedral positions and the Mn valence. Electronic Publication     

Li2 Autler-Townes分裂的实验观察

用光学-光学双共振激光光谱研究了 7Li2A 1Σ+u态的Autler-Townes (A-T) 分裂.一个强的耦合场 (泵浦激光)激发 7Li2A 1Σ+u v′, J′← X 1Σ+g v″, J″跃迁,诱发A 1Σ+u v′, J′能级和 X 1Σ+gv″, J″能级的A-T分裂.另一个探测激光从A 1Σ+u v′,J′能级进一步激发到4 1Σ+g态.扫描探测激光,监测4 1Σ+g态碰撞诱导紫色荧光,从而探测A 1Σ+u v′, J′能级的A-T分裂.当耦合场频率偏离共振时,激发光谱线出现双重分裂.在该实验条件下,分裂大小和泵浦激光频率偏离共振频率的失谐量成正比. 研究了A-T分裂的两条线的相对强度与泵浦、探测光的强度及缓冲气体压力的关系.     

Effect of substituting6Li for7Li on ionic conductivity of α-Li3BO3

The ionic conductivity of γ-Li₃BO₃ is measured in wide intervals of temperatures and⁷Li to⁶Li ratios. It is found that the conductivity and activation energy vary nonmonotonically with variations in concentrations of the two isotopes; the concentration dependence of electroconductivity has a minimum, and that of the activation energy has a maximum at a⁷Li :⁶Li ratio of about 50 : 50 at. %; and the activation energy for conduction by⁶Li exceeds that by⁷Li     

Dominant Li+ ion conduction in Li+/Na+ mixed crystal, 15NaI∙LiBH4

Journal of Solid State Electrochemistry - In the present work, the conduction ions in 15NaI∙LiBH4 are investigated by secondary ion mass spectroscopy (SIMS) and galvanostatic measurements. An...     

Development of ion chromatography and capillary electrophoresis methods for the determination of Li in Li–Al alloy

Two methods were developed for determination Li content in Li–Al alloy by employing ion chromatography (IC) and capillary electrophoresis (CE) without any prior separation of Al matrix. In absence of suitable certified reference material the two methods were used to validate each other. Using a high capacity column and a weaker eluent methane sulphonic acid, it was possible to separate Li in IC without eluting strongly retained Al. The method showed good precision and sensitivity and was extended for analysis of routine samples. In the case of CE using imidazole as co-ion, Li was detected in CE by indirect detection. In view of no interference from Al, samples were analyzed without any matrix separation. The CE method was used successfully for sample analysis and results were compared with IC results.     

Crystal structure of new Li+ ion conducting perovskites: Li2xCa0.5−xTaO3 and Li0.2[Ca1−ySry]0.4TaO3

Two new solid solutions—Li_2xCa_0.5−xTaO₃ (0.05⩽x⩽0.25) and Li_0.2[Ca_1−ySr_y]_0.4TaO₃ (0<y⩽0.15)—based on the A defective ABO₃ perovskite structural type, are synthesized. The crystal structures of these Li⁺ ion conducting compounds are solved from synchrotron radiation and conventional X-ray powder diffraction data. The unit cells exhibit a classical orthorhombic distortion of the cubic perovskite model (space group Pnma No. 62) with parameters close to $\text{2}\text{a}{}_{\mathrm{<mtext>p</mtext>}}$, 2a_p, $\text{2}\text{a}{}_{\mathrm{<mtext>p</mtext>}}$ (a_p, primitive cubic cell parameter). The distortion of the cubic aristotype arises from the three tilts system a⁺b⁻b⁻ of the TaO₆ octahedra. For the same lithium content (x=0.10), the Sr²⁺ substitution to Ca²⁺ is found to enhance the electrical conductivity by quasi-one order of magnitude (at 200 °C, bulk dc conductivity values are close to 2.3×10⁻⁶ and 1.1×10⁻⁵ S cm⁻¹ for Li_0.2Ca_0.4TaO₃ and Li_0.2[Ca_0.9Sr_0.1]_0.4TaO₃, respectively).     

甲烷氧化偶联制乙烯Li—ZrO2,Li—La2O3催化剂的研究

研究了添加Li的La_2O_3和ZrO_2两种催化剂对甲烷氧化偶联催化性能的影响,并用XRD,LRS和XPS等方法对催化剂进行了表征。结果表明,Li~+的加入提高了催化剂的C_2选择性,但两类催化剂上Li~+的添加作用机制不同。La_2O_2加入Li~+达40mol％时,样品可获得34.4％的甲烷转化率和60.4％的C_2选择性。Li~+在La_2O_3表面分散,表面O/(Li+La)比随Li~+添加量增加而下降。催化剂对C_2选择性的提高可能是因为Li~+覆盖了La_2O_3表面部分完全氧化中心所致。ZrO_2中添加Li~+有Li_2ZrO_3生成,75mol％Li-ZrO_2仅检测到Li_2ZrO_3晶相,该样品可得34％甲烷转化率和63％C_2选择性。样品的XRD及XPS研究表明,随Li~+加入量增加,表面Li/Zr比接近2:1,没有Li的富集,样品表面存在两种氧物种,其O_1s结合能分别为530.3和531.9eV。对75mol％Li—ZrO_2样品,后者占95％,该表面氧物种可能与C_2选择性提高有关。     

Li/CDMO电池及其放电机理研究

研究了Li/CDMO电池的放电反应机理、XRD、XPS等实验结果表明, 电池反应是锂在正极内的电化学嵌入反应。用恒电流间隙滴定法(GITT)测得锂在正极中的扩散速率为10^-9cm^2.s^-1量级, 与锂在层状化合物中的扩散速率相当, 结合Li/CDMO电池的热力学行为, Li/CDMO电池的放电反应历程是锂首先客居于层状结构的Li~2MnO~3中, 然后再通过热弛豫进入γ-β-MnO~2的晶格。     

The effects of Mo doping on 0.3Li[Li0.33Mn0.67]O2·0.7Li[Ni0.5Co0.2Mn0.3]O2 cathode material

Mo doped Li excess transition metal oxides formulated as 0.3Li[Li(0.33)Mn(0.67)]O(2)·0.7Li[Ni(0.5-x)Co(0.2)Mn(0.3-x)Mo(2x)]O(2) were synthesized using the co-precipitation process. The effects of the substitution of Ni and Mn with Mo were investigated for the density of the states, the structure, cycling stability, rate performance and thermal stability by tools such as first principle calculations, synchrotron X-ray diffraction, field-emission SEM, solid state (7)Li MAS nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), elemental mapping by scanning TEM (STEM), inductively coupled plasma atomic emission spectrometry (ICP-AES) and a differential scanning calorimeter (DSC). It was confirmed that high valence Mo(6+) doping of the Li-excess manganese-nickel-cobalt layered oxide in the transition metal enhanced the structural stability and electrochemical performance. This increase was due to strong Mo-O hybridization inducing weak Ni-O hybridization, which may reduce O(2) evolution, and metallic behavior resulting in a diminishing cell resistance.     

Li,K∥F,NO3 and Li,K∥Cl,NO3 three-component reciprocal systems

Phase equilibria in Li,K∥F,NO₃ and Li,K∥Cl,NO₃ three-component reciprocal systems were studied by differential scanning calorimetry (DSC). Eutectic compositions (mol %) in the Li,K∥F,NO₃ system were determined to be as follows: 5.0 LiF, 10.0 KF, and 85.0 KNO₃ with T _m = 281°C and 48.5 KNO₃, 44.0 LiNO₃, and 7.5 LiF with T _m = 105°C. Eutectic compositions (mol %) in the Li,K∥Cl,NO₃ system were determined to be as follows: 10.0 LiCl, 32.1 KCl, and 57.9 LiNO₃ with T _m = 147°C and 44.5 KNO₃, 45.0 LiNO₃, and 10.5 KCl with T _m = 97°C.