Magnéli相亚氧化钛陶瓷的制备及其应用研究进展

Magnéli相亚氧化钛是一系列非化学计量比氧化钛的统称,主要包括Ti_(4)O_(7)、Ti_(5)O_(9)、Ti_(6)O_(11)和Ti_(8)O_(15)等相,其中以Ti_(4)O_(7)的导电性最好,其理论电导率可达1500 S·cm^(-1),约为石墨的二倍。此外,Magnéli相亚氧化钛在强酸、强碱环境中均表现出极强的耐蚀性能,并且能够在水溶液中保持3.0 V以上的稳定电位窗口。Magnéli相亚氧化钛优异的性能使其在化学电源如铅蓄电池、液流电池、锂硫电池、可再生燃料电池,电解水的催化剂载体,热电及光电材料,光催化制氢以及电催化氧化降解有机污染物等领域中展现出良好的应用前景。目前,科研人员已经开发出一系列制备亚氧化钛的方法。但是在高纯度、单相、纳米或亚微米尺度亚氧化钛粉体,大尺寸的一体式亚氧化钛电极和金属基亚氧化钛涂层电极的规模化生产和应用中依然存在许多问题,限制了亚氧化钛系列产品在上述领域中的广泛应用。基于Magnéli相亚氧化钛陶瓷的固有特性,重点介绍了亚氧化钛粉体、一体式电极和涂层电极的制备方法及应用现状,同时对亚氧化钛相关材料的应用前景进行了简要概述,为科研院所及相关企业提供了参考依据、研究思路和解决办法。

Biphase-to-monophase structure evolution of Na_(0.766+x)Li_(x)Ni_(0.33-x)Mn_(0.5)Fe_(0.1)Ti_(0.07)O_(2) toward ultradurable Na-ion batteries

Layered composite oxide materials with O3/P2 biphasic crystallographic structure typically demonstrate a combination of high capacities of the O3 phase and high operation voltages of the P2 phase.However,their practical applications are seriously obstructed by difficulties in thermodynamic phase regulation,complicated electrochemical phase transition,and unsatisfactory cycling life.Herein,we propose an efficient structural evolution strategy from biphase to monophase of Na_(0.766+x)Li_(x)Ni_(0.33-x)Mn_(0.5)Fe_(0.1)Ti_(0.07)O_(2) through Li+substitution.The role of Li+substitution not only simplifies the unfavorable phase transition by altering the local coordination of transition metal(TM)cations but also stabilizes the cathode–electrolyte interphase to prevent the degradation of TM cations during battery cycling.As a result,the thermodynamically robust O_(3)-Na_(0.826)Li_(0.06)Ni_(0.27)Mn_(0.5)Fe_(0.1)Ti_(0.07)O_(2) cathode delivers a high capacity of 139.4 mAh g^(-1) at 0.1 C and shows prolonged cycling life at high rates,with capacity retention of 81.6%at 5 C over 500 cycles.This work establishes a solid relationship between the thermodynamic structure evolution and electrochemistry of layered cathode materials,contributing to the development of long-life sodium-ion batteries.

Magneli phase titanium sub-oxide conductive ceramic Ti_nO_(2n-1) as support for electrocatalyst toward oxygen reduction reaction with high activity and stability

Magneli phase titanium sub-oxide conductive ceramic Tin O2n-1 was used as the support for Pt due to its excellent resistance to electrochemical oxidation, and Pt/Tin O2n-1 composites were prepared by the impregnation-reduction method. The electrochemical stability of Tin O2n-1 was investigated and the results show almost no change in the redox region after oxidation for 20 h at 1.2 V(vs NHE) in 0.5 mol/L H2SO4 aqueous solution. The catalytic activity and stability of the Pt/Tin O2n-1 toward the oxygen reduction reaction(ORR) in 0.5 mol/L H2SO4 solution were investigated through the accelerated aging tests(AAT), and the morphology of the catalysts before and after the AAT was observed by transmission electron microscopy. At the potential of 0.55 V(vs SCE), the specific kinetic current density of the ORR on the Pt/Tin O2n-1 is about 1.5 times that of the Pt/C. The LSV curves for the Pt/C shift negatively obviously with the half-wave potential shifting about 0.02 V after 8000 cycles AAT, while no obvious change takes place for the LSV curves for the Pt/Tin O2n-1. The Pt particles supported on the carbon aggregate obviously, while the morphology of the Pt supported on Tin O2n-1 remains almost unchanged, which contributes to the electrochemical surface area loss of Pt/C being about 2times that of the Pt/Tin O2n-1. The superior catalytic stability of Pt/Tin O2n-1 toward the ORR could be attributed to the excellent stability of the Tin O2n-1 and the electronic interaction between the metals and the support.

Structural Analysis and Magnetic Properties of Gd-Doped Li-Ni Ferrites Prepared Using Rheological Phase Reaction Method

A series of Gd-doped Li-Ni ferrites with the formula of LiNi0.5GdxFe2-xO4 where x = 0.00 - 0.08 in steps of 0.02, were prepared by thermolysis of oxalate precursors obtained by rheological phase reaction. The structure, morphology, and the magnetic properties of the samples were characterized by powder X-ray diffraction （XRD）, atomic force microscopy （AFM） and a vibrating sample magnetometer （VSM）. A single spinel phase was obtained in the range of x = 0.00 - 0.04. The lattice parameters of the Gd-doped samples were larger than that of pure Li-Ni ferrite, and increased in the range of 0.00 ≤ x ≤ 0.04, then decreased up to x = 0.08, because of the formation of the secondary phase （Gd- FeO3）. All samples were spheric particles with an average size of about 100 nm, but agglomerated to some extent. The hysteresis loops indicated that the saturation magnetization decreased gradually with increasing Gd content, while the variation of coercivity was related to the microstructure of the Gd-doped samples.

Magnéli相Ti_4O_7的制备及在燃料电池中的应用

综述了制备Magnéli相Ti4O7的H2还原TiO2、C还原TiO2和机械活化Ti和TiO2及两步法合成等4种方法的研究现状及其优缺点,以及研究Magnéli相Ti4O7在燃料电池中的应用现状。展望了软化学法合成高比表面积的Ti4O7材料作为燃料电池催化剂载体材料的发展趋势。

Magnéli相亚氧化钛的制备及其应用

Magnéli相亚氧化钛材料是一类分子式为TinO2n-1(3<n<10)的导电化合物,该类化合物是于20世纪50年代通过XRD技术发现。对这些钛氧化物的制备及其物化性质进行介绍;着重介绍它们在铅蓄电池、液流电池和燃料电池等化学电源电极材料方面的应用进展。

Magnéli相亚氧化钛材料的制备及其可见光光催化性能

以金红石型钛白粉为原料,采用铝还原-盐酸酸洗工艺常压下制备了Magnéli相亚氧化钛材料。采用包括X射线衍射(XRD)仪等多种表征方法测定了制备样品的物相组成、形貌、化学价态及光谱吸收性能,并测试了可见光下样品降解甲基蓝的光催化活性。研究结果表明:950℃焙烧15~30min条件下制备的Magnéli相亚氧化钛材料主要为Ti_(4)O_(7)和Ti5O9的混合相,采用盐酸酸洗可以有效去除样品中的Al,但含有不溶于酸的α-Al_(2)O_(3)。该工艺制备的Magnéli相亚氧化钛颗粒尺寸为100~200nm,没有存在明显的团聚烧结长大现象,具有良好的可见光和近红外光吸收性能以及在可见光条件下具有较好的光催化能力。

Magnéli相亚氧化钛的制备和应用研究进展

介绍了当前制备亚氧化钛的几种常见方法,以及亚氧化钛材料的应用现状,并对亚氧化钛材料的前景进行了简要分析。虽然当前该种材料在制备上存在一些问题,但经过相应改进后该材料能够实现大规模合成,展现出更大的应用价值。

Ti-O Magnéli相氧化物的性质、制备与应用研究进展

Ti-O Magnéli相氧化物因具有特殊的结构和性质自发现以来就备受关注。Ti-O Magnéli相氧化物优良的电子导电性、稳定性以及耐腐蚀性使得其在电化学领域应用广泛。综述了Ti-O Magnéli相氧化物的组成、结构、性质及其主要的制备方法,并总结归纳了该材料的主要应用。提供了Ti-O Magnéli相氧化物未来合成与应用研究的方向。

Li intercalation in an MoSe_(2) electrocatalyst:In situ observation and modulation of its precisely controllable phase engineering for a high-performance flexible Li-S battery

Sophisticated efficient electrocatalysts are essential to rectifying the shuttle effect and realizing the high performance of flexible lithium-sulfur batteries(LSBs).Phase transformation of MoSe_(2) from the 2H phase to the 1T phase has been proven to be a significant method to improve the catalytic activity.However,precisely controllable phase engineering of MoSe_(2) has rarely been reported.Herein,by in situ Li ions intercalation in MoSe_(2),a precisely controllable phase evolution from 2H-MoSe_(2) to 1T-MoSe_(2) was realized.More importantly,the definite functional relationship between cut-off voltage and phase structure was first identified for phase engineering through in situ observation and modulation methods.The sulfur host(CNFs/1T-MoSe_(2))presents high charge density,strong polysulfides adsorption,and catalytic kinetics.Moreover,Li-S cells based on it display capacity retention of 875.3mAh g^(-1) after 500 cycles at 1 C and an areal capacity of 8.71mAh cm^(-2) even at a high sulfur loading of 8.47mg cm^(-2).Furthermore,the flexible pouch cell exhibiting decent performance will endow a promising potential in the wearable energy storage field.This study proposes an effective strategy to precisely control the phase structure of MoSe_(2),which may provide the reference to fabricate the highly efficient electrocatalysts for LSBs and other energy systems.

Magnéli相亚氧化钛电极的制备及应用

简要阐述了常规电催化氧化阳极材料及电催化氧化机理,归纳总结了Magnéli相亚氧化钛电极的性质及不同制备手段的优缺点。对近年来国内外Magnéli相亚氧化钛电极在电催化氧化处理新污染物废水的应用进行了综述,并从电极制备及性质上进行了分析,对Magnéli相亚氧化钛电极的应用前景和发展方向进行了展望。

Effect of Li on formation of long period stacking ordered phases and mechanical properties of Mg-Gd-Zn alloy

Alloys with composition of Mg_(96-x)Gd_3Zn_1Li_x(at.%)(x=0, 2, 4, and 6) were prepared by conventional casting. The microstructures of these alloys under as-cast and solid-solution conditions have been observed, and the mechanical properties were investigated. The results showed that Li is an effective element to refine the grains and break the eutectic networks in as-cast MgGd_3Zn_1 alloy. During solid solution treatment, these broken eutectic networks are spheroidized and highly dispersed. In addition, plentiful lamellar long period stacking ordered(LPSO) phases are precipitated in an α-Mg matrix when the Li addition is not more than 4%. Solid-solution treated Mg_(92)Gd_3Zn_1Li_4 alloy exhibits an optimal ultimate tensile strength(UTS) of 226 MPa and elongation of 5.8%. The strength of MgGd_3Zn_1 alloy is improved significantly, meanwhile, the toughness is apparently increased.

预变形量对2050 Al−Li合金显微组织和力学性能的影响

研究经不同轧制预变形处理(0~20%)后2050 Al−Li合金T8时效状态的显微组织演变和力学性能。通过透射电子显微镜(TEM)和扫描电子显微镜(SEM)对其显微组织进行表征。结果表明:随着预变形量的增加,晶粒尺寸沿ND方向显著变小,晶内畸变增大。位错等的缠结为T1相的析出提供了大量的形核位点。这导致析出相数量增多,析出相之间的距离缩小,从而提高了对位错运动的阻碍作用和合金强度。当预变形量为16%时,T1相数量密度和合金强度最高(屈服强度和抗拉强度分别达到568和584 MPa,伸长率为8.6%);当预变形量进一步增加到20%时,由于位错缠结,原子扩散通道减少,T1相数量的减少最终导致合金强度降低。

Phase Equilibria of the Aqueous Systems Containing Lithium and Carbonate Ions

1 Introduction Alkaline lakes are widely distributed in the area of the Qinghai-Tibet Plateau.Most of the salt lakes are famous for their high concentration of lithium,potassium,magnesium,boron(Ma,2000).In recent years,as a new energy material,lithium and its compounds are widely used in the new area,such as aerospace industry,nuclear

Electronic Phase Separation in Iron Selenide(Li,Fe)OHFeSe Superconductor System

The phenomenon of phase separation into antiferromagnetic（AFM） and superconducting（SC） or normal-state regions has great implication for the origin of high-temperature（high-T_c） superconductivity. However, the occurrence of an intrinsic antiferromagnetism above the T_c of（Li,Fe）OHFe Se superconductor is questioned. Here we report a systematic study on a series of（Li,Fe）OHFe Se single crystal samples with T_c up to ～41 K. We observe an evident drop in the static magnetization at T_（afm） ～ 125 K, in some of the SC（T_c 38 K, cell parameter c■9.27 ？） and non-SC samples. We verify that this AFM signal is intrinsic to（Li,Fe）OHFe Se. Thus, our observations indicate mesoscopic-to-macroscopic coexistence of an AFM state with the normal（below T_（afm）） or SC（below T_c） state in（Li,Fe）OHFe Se. We explain such coexistence by electronic phase separation, similar to that in high-T_c cuprates and iron arsenides. However, such an AFM signal can be absent in some other samples of（Li,Fe）OHFe Se, particularly it is never observed in the SC samples of T_c 38 K, owing to a spatial scale of the phase separation too small for the macroscopic magnetic probe. For this case, we propose a microscopic electronic phase separation. The occurrence of two-dimensional AFM spin fluctuations below nearly the same temperature as T_（afm）, reported previously for a（Li,Fe）OHFe Se（T_c ～ 42 K） single crystal, suggests that the microscopic static phase separation reaches vanishing point in high T_c（Li,Fe）OHFe Se. A complete phase diagram is thus established. Our study provides key information of the underlying physics for high-T_c superconductivity.

Cu含量对Al-Cu-Li合金淬火敏感性的影响

采用薄板叠层末端淬火的方法,通过强度测试、连续冷却转变(CCT)和时间-温度-转化率(TTT)曲线计算及X射线衍射、扫描电镜、透射电镜等微观组织表征方法,研究了Cu含量(3.15%、3.63%和3.88%)对Al-Cu-Li合金淬火敏感性的影响,结合理论分析,从析出驱动力和形核位点的角度分析了Cu含量影响淬火敏感性的机理。结果表明:随着Cu含量的增加,晶格畸变能增加,Li的溶解度降低,淬火态合金中位错和残留第二相增多,含Li相的析出驱动力和非均匀形核位点增加,淬火沉淀相增多;随着临界冷却速率的增大,鼻尖温度孕育期缩短,强度残存率减小,Al-Cu-Li合金淬火敏感性提高。T8态合金强度受Cu含量和淬火速率共同作用,淬火速率较高时,主要受Cu含量的影响;淬火速率较低时,Cu含量的影响减小。

Unexpected Li displacement and suppressed phase transition enabling highly stabilized oxygen redox in P3-type Na layered oxide cathode

Oxygen redox is considered a new paradigm for increasing the practical capacity and energy density of the layered oxide cathodes for Na-ion batteries. However, severe local structural changes and phase transitions during anionic redox reactions lead to poor electrochemical performance with sluggish kinetics.Here, we propose a synergy of Li-Cu cations in harnessing the full potential of oxygen redox, through Li displacement and suppressed phase transition in P3-type layered oxide cathode. P3-type Na_(0.7)[Li_(0.1)Cu_(0.2)Mn_(0.7)]O_(2) cathode delivers a large specific capacity of ~212 mA h g^(-1)at 15 mA g^(-1). The discharge capacity is maintained up to ~90% of the initial capacity after 100 cycles, with stable occurrence of the oxygen redox in the high-voltage region. Through advanced experimental analyses and first-principles calculations, it is confirmed that a stepwise redox reaction based on Cu and O ions occurs for the charge-compensation mechanism upon charging. Based on a concrete understanding of the reaction mechanism, the Li displacement by the synergy of Li-Cu cations plays a crucial role in suppressing the structural change of the P3-type layered material under the oxygen redox reaction, and it is expected to be an effective strategy for stabilizing the oxygen redox in the layered oxides of Na-ion batteries.

Al−Cu−Li−Mg合金纳米相之间溶质配分行为的第一性原理研究

采用一性原理计算考察25种合金化元素在大多数商业牌号Al−Cu−Li−Mg合金中主要纳米相(δʹ-Al3Li、θʹ-Al2Cu、T1-Al6Cu4Li3和S-Al2CuMg)之间的溶质配分能和配分行为。计算结果表明,主合金化元素Li不能直接影响θʹ和S相,Cu不能直接影响δʹ相,Mg不能直接影响θʹ和δʹ相,但可以较弱地固溶于T1相。对于微合金化元素,Si是唯一一种可以固溶于4种纳米相的元素。Au能固溶于δʹ、θʹ和S相,Cd能固溶于δʹ、T1和S相,Zr能固溶于δʹ和T1相,Ni仅有微弱的趋势固溶于θʹ和S相。Ti、V、Zn、Ag和Mo只能固溶于δʹ相,而Cr、Mn、Fe和Co对这4种纳米相均没有直接影响。几乎所有的稀土元素均能强烈固溶于T1、δʹ和S相,但无法固溶于θʹ相。仅Sc略显特殊,对S相没有明显的固溶趋势。计算预测的溶质配分能构成了一个原型数据库,有利于指导和加速Al−Li合金及其他相关Al合金的设计。

Phase diagrams of Li_2MoO_4-Na_2MoO_4 and Na_2MoO_4-K_2MoO_4 systems

The phase diagrams of the Li2MoO4-Na2MoO4 and Na2MoO4-K2MoO4 systems have been reassessed using differential thermal analysis together with high-temperature and room-temperature X-ray diffraction analysis. The results showed that the compound Li2MoO4.6Na2MoO4 did not exist; however, it confirmed the existence of the compound Li2MoO4.3Na2MoO4 in the Li2MoO4-Na2MoO4 systen＇ls. With regard to the system of Na2MoO4-K2MoO4, we could not confirm the results reported by Bukhanova who claimed that the system was eutectic type with 1：1 and 1：2 intermediate compounds, refuting the statement of Amadori who thought there was an apparent phase boundary at high temperature in α-solid solution region of the Na2MoO4-K2MoO4 binary system. The revised phase diagrams of these systems are illustrated in this article. These experimental results are in agreement with the computerized prediction using the support vector machine-atomic parameter method for the assessment of phase diagrams.

Li掺杂对铜锌锡硫硒太阳电池的影响研究

开展了基于二甲基亚砜溶剂体系的溶胶凝胶法制备铜锌锡硫硒薄膜中掺杂Li的相关研究。对不同Li掺杂量的CZTSSe薄膜分别进行了表截面形貌、晶体结构、成分比例测试,结果表明:在CZTSSe薄膜中掺杂Li可以提升薄膜的结晶质量,且随着Li掺杂量的增加,结晶质量变好。分析原因为,高温硒化过程中形成的Li_(2)Se相辅助生长改善了薄膜的结晶质量,抑制了ZnCu和SnCu等施主能级缺陷生成。但是,同样发现在Li/Cu摩尔比为1%~10%之间存在阈值,过量的Li并不能进入晶格而富集在晶界处。对不同Li掺杂的CZTSSe薄膜进行太阳电池的制备,结果表明Li/Cu为1%的太阳电池具有最高的转换效率,达到8.5%。