无锂助熔剂B_2O_3对Li_(1.3)Al_(0.3)Ti_(1.7)(PO_4)_3固体电解质离子电导率的影响

采用固相法制备锂离子电池用固体电解质磷酸钛锂铝Li_(1.3)Al_(0.3)Ti_(1.7)(PO_4)_3(LATP),研究了不同烧结温度以及助熔剂对LATP固体电解质离子电导率的影响.采用X射线衍射、能谱分析、扫描电镜和交流阻抗等方法,研究样品的结构特征、元素含量、形貌特征以及离子导电性能.结果表明,在900?C烧结可以获得结构致密、离子电导率较高的纯相LATP陶瓷固体电解质.与添加助熔剂Li BO2的样品进行对比实验发现,采用B_2O_3代替LiBO_2作为助熔剂也可以提高烧结样品的离子电导率,并且电解质的离子电导率随助熔剂添加量的增大,先增大后减小,其中添加质量百分比为2%的B_2O_3的样品具有最高的室温离子电导率,为1.61×10~(-3)S/cm.     

多晶Li_(3+x)V_(1-x)T_xO_4(T=Ge,Si)离子导电性能的改善

本文用阻抗谱方法研究了Li_(3+x)V_(1-x)T_xO_4(T=Si,Ge)多晶的离子导电性,发现一些工艺条件如成型压强、烧结时间和烧结程序对电导率有很大影响。注意分析了这些影响的物理起因。最佳工艺条件是:在大约8t/cm~2压强下成型样品。在1000℃连续烧结5至6天,烧结过程中,应尽量避免温度波动。在此条件下制备的Li_(3.5)V_(0.5)Ge_(0.5)O_4和Li_(3.3)V_(0.7)Si_(0.3)O_4多晶样品在25℃的离子电导率分别为2.2×10~(-5)Q~(-1)cm~(-1)和1.9×10~(-5)Q~(-1)cm~(-1)。     

Li_(1+x)Ge_(2-x)Al_xP_3O_(12)系统的相关系和电导

本文研究了Li_(1+x)Ge_(2-x)Al_xP_3O_(12)系统的相组成和电导的关系。发现用LiGe_2P_3O_(12)作为基体化合物,通过离子置换可以得到好的锂离子导体。用Al~(3+)置换LiGe_2P_3O_(12)中的Ge~(4+),在00.6时出现未知相,用少量Al~(3+)取代Ge~(4+)后电导率即突增,在固溶体范围内电导率随x值的增大而继续升高。x=0.5时达极大值。Li_(1.5)Ge_(1.5)Al_(0.5)P_3O_(12)在室温、300℃和450℃的电导率分别为3.5×10~(+5),1×10~(-2)和3.1×10~(-2)S cm~(-1),电导活化能为0.33eV,电子迁移数在10~(-5)数量级。     

Li_4SiO_4-Li_3VO_4赝二元系和Li_4GeO_4-Li_4SiO_4-Li_3VO_4赝三元系中新的锂离子导体

本文在室温到300℃的温度范围内研究了Li_4SiO_4-Li_3VO_4和Li_4GeO_4-Li_4SiO_4-Li_3VO_4体系中的离子导电性,发现γ_(II)相固溶体Li_(3 x)V_(1-x)Si_xO_4是好的锂离子导体。所研究的成分中Li_(3.3)V_(0.7)Si_(0.3)O_4的离子电导率最高,室温下为1×10~(-5)Q~(-1)·cm~(-1),在42—192℃的电导激活能为0.36eV,电子电导率可以忽略,因而这是迄今所发现的最好的锂离子导体之一。粗略确定了Li_4GeO_4-Li_4SiO_4-Li_3VO_4三元系中电导率高的范围,发现在Li_(3.5)V_(0.5)Ge_(0.5)O_4中Si部分取代Ge可以使电导率进一步提高,Li_(3.5)V_(0.5)Ge_(0.4)Si_(0.1)O_4的室温电导率可达1.3×10~(-5)Q~(-1)·cm~(-1),电导激活能为0.40eV。     

镨掺杂对无钴钙钛矿型氧化物BaFeO_(3-δ)电导率和透氧性能的影响（英文）

本文尝试通过镨部分取代铁来改善无钴型钙钛矿材料BaFeO_(3-δ)在室温下的结构稳定性,考察镨掺杂对材料导电及透氧性能的影响,获得新型的高性能无钴透氧膜材料.实验中通过固相反应法合成了BaFe_(3-y)Pr_yO_(3-δ)(y=0、0.025、0.05、0.075、0.1)复合粉末,并由此制得烧结体样品.XRD测试结果表明,BaFe_(3-y)Pr_y O_(3-δ)材料在镨掺杂量为(y=0.05、0.075、0.1)时仍然保持立方相,这表明掺杂Pr~(n+)有利于材料立方相结构的稳定.SEM观测表明,烧结样品中仅含有少量闭孔,说明Pr~(n+)的掺杂促进了烧结致密化.电导率和透氧率测试结果表明,900℃时,BaFe_(0.9)Pr_(0.1)O_(3-δ)的电导率和透氧率分别为6.5L/cm和1.112 mL/(cm~2.min),镨掺杂可以改善BaFe_(1-y)Pr—yO_(3-δ)材料的传导性能.高温XRD结果表明,BaFe_(0.975)Pr_(0.025)O_(3-δ)的晶体结构在700℃完全转变为立方相.BaFe0_3中Pr~(n+)对Fe~(m+)的部分取代可以稳定立方相结构,提高BaFe_(1-y)Pr_yO_(3-δ)的导电性和透氧率.     

Bi_2O_3-Y_2O_3系高氧离子导体的离子电导和电子电导的研究

用交流电桥法研究了Bi_2O_3 Y_2O_3体系含22.5—30mol％Y_2O_3烧结试样在po_2值由1至10~(-21)atm范围内氧离子的电导率,实验证明该种材料的氧离子电导率比同温度下ZrO_2基固体电解质高若干倍;用这种材料作为固体电解质组成氧浓差电池,电池电动势和理论电动势的比值E/E_0等于1或接近1,说明这种材料几乎为纯氧离子导体,p型电子空穴导电性很小;用库伦滴定抽氧法测定了含Y_2O_3 27.5mol％样品的电子导电特征氧分压,其值为lgpe＇=(-767000/T)+655,电子导电性极小。可期望为一种新型氧离子导体材料。     

含分散第二相混合导体Li1＋xV3O8（x=0.1）的磁共振研究

本文研究了含分散第二相混合导体Li_1 x~(V_3O_8)(x=0.1 )体系的电性能和磁共振现象.经AC测定:表明室温下含6mol％α-Al_2O_3样品的总电导率是不含第二相样品的4-6倍.由ESR和NMR定性、定量分析确定分散第二相微粒的加入,增加了样品的电子浓度,加快了样品中电子和离子的跃迁频率,降低了样品中Li~ 离子迁移激活能,总电导率增加.室温下,总电导率的增量主要取决于Li~ 离子电导率的贡献,电子电导率也有一定影响.     

Al~(3+)/Mo~(6+)双离子取代ZrV_2O_7中Zr~(4+)/V~(5+)实现近零膨胀

采用固相烧结法制备了Zri_(1-x)Al_(2-x)V_(2-x)Mo_xO_7(0≤x≤0.9),并通过调整Al~(3+)/Mo~(6+)对ZrV_2O_7中的Zr~(4+)/V~(5+)离子替代量来实现近零膨胀,对于较小的x值(x≤0.3),材料保持了与ZrV_2O_7相同的立方相结构.随着Al~(3+)/Mo~(6+)替代量的增加,(Al/Zr)~-和(Mo/V)~+之间的库仑相互作用逐渐加强,这种库仑相互作用导致材料中未发生畸变的立方相晶体结构逐渐减少.当x≥0.7时,材料中立方相晶体结构完全消失.在425-750 K温度区间内,Zr_(0.5)Al_(0.5)M_(0.6)O_7展示出近零膨胀性质(-0.39×l0~(-6)K~(-1)).Zr_(0.5)Al_(1.5)V_(1.5)Mo_(0.5)O_7的低热膨胀性能可能与Al~(3+)/Mo~(6+)对ZrV_2O_7中Zr~(4+)/V~(5+)部分替代引起部分晶体结构发生的畸变及其对未替代部分的晶格结构的影响有关.     

Na_3Zr_(2-x)In_xSi_(2-x)P_(1 x)O_(12)系统的组成、结构和离子电导的关系

用固相反应、X射线衍射、金相显微镜观察、测定比热和复平面阻抗谱的方法研究了Na_3Zr_(2-x)In_xSi_(2-x)P_(1 x)O_(12)系统。 在此系统中存在两种固溶体:单斜固溶体(0≤x<0.8)和三方固溶体(0.8≤x≤1.8)。即从x=0.8的组成开始,NASICON型Na_3Zr_(2-x)In_xSi_(2-x)P_(1 x)O_(12)固溶体的三方型相已稳定在室温,在加热过程中不再有相变出现。 对Na_3Zr_(2-x)M_xSi_(2-x)P_(1 x)O_(12)(M=Y,Yb和In)系统的电导率进行了比较,并从结晶化学的角度进行了讨论。     

非晶态锂离子导体B_2O_3-0.7Li_2O-0.7LiCl-xAl_2O_3-0.1V_2O_5的电学性质和电子自旋共振研究

对两种非晶态B_2O_3-0.7Li_2O-0.7LiCl-xAl_2O_3-0.1V_2O_5(x=0.05和0.15),用差热分析、电导率测量、X射线衍射和电子自旋共振进行研究,发现:1)V_2O_5不仅作非晶网络形成剂,而且改变了晶化过程;2)对B_2O_3-Li_2O-LiCl-Al_2O_3-V_2O_5玻璃,与P_2O_5-Li_2O-LiCl-Al_2O_3玻璃类似,粉末压片的离子电导率比60目粉末大26倍,而整片非晶的离子电导率又比粉末压片大近二个数量级,而且激活能明显减小,更适合离子传输;3)添加少于3.9mol%的V_2O_5,对非晶态锂离子导体B_2O_3-0.7Li_2O-0.7LiCl-xAl_2O_3,未引起电子电导率显著增大,又可应用电子自旋共振(ESR)技术研究其微观结构和电子运动状态。     

Synthesis,structural and conductive properties of Nd doped garnet-type Li7La3Zr2O12 Li-ion conductor

Garnet type solid electrolyte Li₇La₃Zr₂O₁₂ (LLZO) is the most promising candidate among solid electrolytes for all solid state Li batteries. In this work, small amount of Nd doping (5%–20%) to the garnet structure is proposed to improve its ionic conductivity. Nd doped garnet type solid electrolytes for Li-ion batteries were synthesized through a conventional solid state reaction method. The effect of Nd doping on the microstructure, morphology and ionic conductivity of the LLZO was studied by powder X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, Field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS) and Electrochemical impedance spectroscopy (EIS) methods. Instead of La whose valence is similar to that of Nd, XRD and Raman analyzes revealed that Nd takes the place of the higher valence element Zr. In order to compensate the valence difference, the ratio of Li increases in the structure. On the other side, results showed that Nd doped LLZO samples formed as a mixture of both tetragonal and cubic phases. According to EIS measurements, among the prepared samples, 5% Nd doped LLZO exhibits the highest ionic conductivity of 2.47 × 10⁻⁶ S cm⁻¹ at room temperature.     

Effect of Al-Mo codoping on the structure and ionic conductivity of sol-gel derived Li<Subscript>7</Subscript>La<Subscript>3</Subscript>Zr<Subscript>2</Subscript>O<Subscript>12</Subscript> ceramics

Al-Mo codoped Li₇La₃Zr₂O₁₂ ceramics with fine grain were prepared by sol-gel method. The influences of Al-Mo codoping on the structure, microstructure, and conductivity of Li₇La₃Zr₂O₁₂ were investigated by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and impedance spectroscopy. The cubic phase Li₇La₃Zr₂O₁₂ has been stabilized by partial substitution of Al for Li and Mo for Zr. Li_6.6-3yAl_yLa₃Zr_1.8Mo_0.2O₁₂ (0?≤?y?≤?0.1) has been sintered at 1040–1060 °C for 3 h. The liquid sintering facilitated its densification. The relative density of the composition with x?=?0.075 was approximately 96.4%. Results indicated that the Al-Mo codoped LLZO synthesized by sol-gel method effectively lowered its sintering temperature, accelerated densification, and improved the ionic conductivity.     

Effect of B-site substitution of (Li,La)TiO3 perovskites by di-, tri-, tetra- and hexavalent metal ions on the lithium ion conductivity

We report the synthesis and lithium ion conductivity of di-, tri-, tetra- and hexavalent metal ion B-site substituted (Li,La)TiO₃(LLT) perovskites. All 5–10 mol% Mg, Al, Mn, Ge, Ru and W ion substituted LLTs crystallize in a simple cubic or tetragonal perovskite structure. Among the oxides investigated, the Al-substituted perovskite La_0.55Li_0.36□_0.09Ti_0.995Al_0.005O₃ (□=vacancy) exhibits the highest lithium ion conductivity of 1.1 × 10⁻³ S/cm at room temperature which is slightly higher than that of the undoped (Li,La)TiO₃ perovskite (8.9 × 10⁻⁴ S/cm) at the same temperature. The lithium ion conductivity of substituted LLTs does not seem to depend on the concentration of the A-site ion vacancies and unit cell volume. The high ionic conductivity of Al-substituted LLT is attributed to the increase of the B(Al)-O bond and weakening of the A(Li,La)-O bond. The conductivity behavior of the doped LLT is being described on the basis of Gibbs free energy considerations.     

Dramatic reduction in the densification temperature of garnet-type solid electrolytes

Cubic garnet Li₇La₃Zr₂O₁₂ (LLZO) and similar compositions of fast ion-conducting solid-state electrolytes have shown great potential for the development of high-energy-density solid-state Li-ion batteries. Although these materials have shown unprecedented ionic conductivities and chemical stability, these materials require high processing temperatures for synthesis. For many of the common compositions of LLZO, temperatures above 1000 °C are required to form the cubic garnet phase and to achieve high conductivities. Therefore, lowering the processing temperatures of these materials is of great interest for the purposes of scalability and fabrication. It has been reported that a Bi co-dopant not only stabilizes the cubic garnet phase but also lowers the densification temperature. In this study, Li₆La₃ZrBiO₁₂ (LLZBO) was prepared by a rapid-induction hot-pressing technique and characterized using a variety of techniques, including X-ray diffraction, scanning electron microscopy, and Raman spectroscopy. We demonstrate the ability to synthesize phase-pure LLZBO with higher relative densities (~?94%) than can be achieved by pressure-less sintering methods, at pressing temperatures of only 850 °C. The ionic conductivity was measured to be 0.1 mS cm^?1, which is comparable to the best reported conductivities of high-density LLZO. This demonstrates the ability to fabricate dense, phase-pure, and high-conductivity LLZBO at temperatures significantly lower than other garnet compositions, which will prove useful for scalability and reducing reactivity with cathodes during densification.     

An ab initio molecular dynamics study of ionic conductivity in hexagonal lithium lanthanum titanate oxide La0.5Li0.5TiO3

To date, the fastest lithium ion-conducting solid electrolytes known are the perovskite-type ABO₃ oxide, with A = Li, La and B = Ti, lithium lanthanum titanate (LLTO) Li_3x La_{( 2 \mathord}

Structure and lithium ionic conduction mechanism in La4/3−yLi3yTi2O6

The solid solutions La_4/3−yLi_3yTi₂O₆ (y=0.09∼0.33) have been studied by complex impedance spectroscopy, X-ray diffraction (XRD) and nuclear magnetic resonance (NMR) methods. The ionic conductivity shows a maximum value at around y=0.21, and keeps high values at high y concentrations. The XRD patterns show a single phase for all concentration. The crystal structure is orthorhombic with space groupPmmm for y=0.09∼0.15 and tetragonal with space groupP4/mmm for y=0.17∼0.33. The⁷Li static NMR spectra show a main central peak with a Lorenzian shape for y=0.09∼0.21. The central peak is divided into two parts for y=0.23∼0.33. The narrow intense peak is a mobile component due to mobile ions, and a small broad central peak is due to less mobile lithium ions which contribute to immobile component. The⁷Li MAS NMR spectra show negative chemical shifts which decrease with increasing y concentration. In this paper, we discuss the conduction mechanism and the structure from the analysis of conductivity, lattice parameters, occupation, atomic positions and the⁷Li static/MAS NMR spectra.     

Computational screening of doping schemes for LiTi2(PO4)3 as cathode coating materials

In all-solid-state lithium batteries,the impedance at the cathode/electrolyte interface shows close relationship with the cycle performance.Cathode coatings are helpful to reduce the impedance and increase the stability at the interface effectively.LiTi2(PO4)3(LTP),a fast ion conductor with high ionic conductivity approaching 10^-3S·cm^-1,is adopted as the coating materials in this study.The crystal and electronic structures,as well as the Li^+ion migration properties are evaluated for LTP and its doped derivatives based on density functional theory(DFT)and bond valence(BV)method.Substituting part of Ti sites with element Mn,Fe,or Mg in LTP can improve the electronic conductivity of LTP while does not decrease its high ionic conductivity.In this way,the coating materials with both high ionic conductivities and electronic conductivities can be prepared for all-solid-state lithium batteries to improve the ion and electron transport properties at the interface.     

Lithium ionic jump motion in the fast solid ion conductor Li(5)La(3)Nb(2)O(12)

Using (7)Li NMR line-shape analysis, spin-lattice relaxation measurements and stimulated-echo spectroscopy, we investigate the lithium ionic jump motion in the garnet Li(5)La(3)Nb(2)O(12). Results for two samples are compared, which were annealed at 850( composite function)C (GR-850) and at 900( composite function)C (GR-900), respectively. All (7)Li NMR data consistently show that two lithium species with distinguishable dynamical behaviors coexist in each of the samples. While the less mobile species is the majority component in GR-850, the more mobile species is the majority component in GR-900. (7)Li NMR stimulated-echo spectroscopy provides straightforward access to the correlation functions describing the jumps of the respective majority component in both samples. From the temperature-dependent correlation times, we obtain activation energies of 56 and 32kJmol(-1) for GR-850 and GR-900, respectively. For both samples, the correlation functions substantially deviate from simple exponential behavior, indicating a high complexity of the lithium ionic motion in Li(5)La(3)Nb(2)O(12).     

非晶锂离子电导率的压力效应

 本文准确测量了0~2.21 GPa流体静压力下整体片状非晶B₂O₃-0.7Li₂O-0.7LiCl-0.10Al₂O₃及其粉末样品的离子电导率和激活体积。对整片非晶锂离子电导率的压力效应应用离子迁移通道的物理图象给出初步的微观解释。对非晶粉末样品离子电导率的压力效应，则发现是由体电导率、接触电导率及同相界面电导率变化的综合结果。高压实验表明，同相界面效应可使离子电导率提高2.5~16倍，该非晶材料还有潜力可进一步提高其离子电导率。     

High-pressure phases in the GaSb-Mn system

The effect of high pressure (6 GPa) on the formation of new phases in a polycrystalline mixture GaSb: Mn = 1: 1 upon heating was studied. Sphalerite-type solid solutions with a small amount of Mn form at temperatures below 520–600 K. At higher temperatures, new crystalline GaSbMn phases are synthesized: a phase with a simple cubic structure with a lattice parameter a = 2.946 ± 0.001 Å (at 620–670 K) and a phase with a tetragonal CuAl₂-type structure (space group I4/mcm) with lattice parameters a = 6.426 ± 0.004 Å and c = 5.349 ± 0.004 Å (at 690–870 K). These new phases are metastable under normal conditions and have magnetic properties. The structure, conductivity, and thermal stability of the synthesized phases are investigated, and the products of decomposition of these new phases upon annealing are analyzed.