工艺参数对o-LiMnO2相纯度及Li1.6Mn1.6O4合成的影响及作用（英文）

以MnSO4,KMnO4及LiOH为原料,经水热处理后得到LiMnO2,再由固相焙烧得到尖晶石相Li1.6Mn1.6O4,酸洗处理后得到锂离子筛。研究了水热温度,氧气和MnO4-/Mn2+的物质的量之比(nMnO4∶nMn^2+)对所得LiMnO2的组成及相应前驱体Li1.6Mn1.6O4酸处理中Mn溶损率的影响。开路电势测量及化学分析表明,氧气会参与反应。若按照理论氧化剂用量nMonO4∶nMn^2+=1∶4进行水热反应会导致杂质Li2MnO3和LiMn2O4的生成。若控制水热温度为160℃,nMnO4∶nMn^2+=1∶6时可得到纯相正交LiMnO2(o-LiMnO2)。所得离子筛在高镁锂比盐湖卤水中Li+吸附容量可达42.87 mg·g^-1,且对Li+具有优异的选择吸附性并遵循化学吸附过程。经过5个循环后吸附容量保持在37.21 mg·g^-1,锰溶损率降至0.34%。     

Solvothermal Synthesis of Superfine Li1−xMn2O4−σ Powders

Superfine Li_1−xMn₂O_4−σ powders were successfully synthesized by the alcohol-thermal method using 0.01 mol of MnO₂, 0.01mol of LiOH·H₂O, and 0.06mol of NaOH as starting materials at 160-200°C. The products are characterized by XRD, TEM, ED, BET, and ICP. Results show that the Li_0.74Mn₂O_3.74 powder prepared at 200°C has an average size of 180 nm with BET surface areas of 16.44 m²/g. A possible formation mechanism is proposed. It was concluded that the alcohol acts not only as the solvent but also as the reducing agent in the synthesis of Li_1−xMn₂O_4−σ powders. The effects of reaction temperature and the contents of NaOH and LiOH on the formation of single phase Li_1−xMn₂O_4−σ were investigated.     

锂离子电池正极材料层状LiNi1/2Mn1/2O2的制备与表征

用一种简单的共沉淀法制备出了层状LiNi_1/2Mn_1/2O₂材料，并且用XRD、SEM、循环充放电、循环伏安(CV)和电化学阻抗谱(EIS)等方法对材料进行了表征测试。首先，用共沉淀法制备氢氧化镍和氢氧化锰的混合物;然后，对共沉淀溶液进行预氧化来制备前驱体;最后，用预氧化的前驱体合成了LiNi_1/2Mn_1/2O₂材料。SEM和XRD测试结果分别表明:LiNi_1/2Mn_1/2O₂材料是粒径范围在100～200 nm之间的球形粒子，并且具有非常好的层状结构。循环充放电表明:在空气中900 ℃下合成时间为9 h的材料，在充放电截止电压为2.8～4.6 V的情况下，经过40次循环，材料的容量可以稳定地保持在140 mAh·g^-1左右。循环伏安曲线表明:在锂的初始脱嵌和入嵌过程中存在不可逆相变。电化学阻抗谱测试表明LiNi_1/2Mn_1/2O₂具有很好的锂离子扩散能力。     

Mn2O3纳米结构的简易合成与电化学性质

用简易的室温或水热方法制备出不同形貌的MnCO₃微结构。经600 ℃热处理后,室温制备MnCO₃转变成Mn₂O₃胶体片,而水热制备MnCO₃样品则形成多孔Mn₂O₃纳米结构。然而,室温制备MnCO₃经120 ℃热处理后形成Mn₂O₃晶相。制备样品经过XRD和SEM表征表明,热处理MnCO₃前驱物形成Mn₂O₃过程导致产物形貌与结构变化。其形成机理又通过TEM和FTIR进一步研究。Mn₂O₃纳米结构的电容性质通过循环伏安法表征,结果表明Mn₂O₃形貌与结构对其电容有重要影响。     

Li2O-TiO2-SiO2-P2O5和Li2O-TiO2-Al2O3-P2O5体系锂离子固体电解质的制备及性能研究

一些具有NASICON型网格结构的固体电解质具有高的电导率和好的稳定性,NASICON的意思是Na Super Ionic Conductor[1]。当NaZr2(PO4)3中P5 被Si4 部分取代时便可以得到具有NASICON结构的Na1 xZr2SixP3-xO12体系,其具有高的钠离子电导率。然而有相同结构的Li1 xZr2SixP3-xO12体系的离子电导率却很低,这是因为Li 半径太小,而NASICON三维网格结构的离子通道太大,两者不匹配而使电导率下降[2]。但当LiZr2(PO4)3中Zr4 被离子半径小些的Ti4 取代,所得LiTi2(PO4)3的通道就与Li 半径相匹配,适合于锂离子的迁移,从而使其电导率…     

Li2CO3、NiO和电解MnO2合成高容量LiNi0.5Mn1.5O4及其表征

Well-developed crystalline LiNi_0.5Mn_1.5O₄ was prepared by solid-state reaction using Li₂CO₃, NiO and electrolytic MnO₂ at high heating and cooling rate. X-ray diffraction (XRD) patterns and scanning electron microscopic (SEM) images showed that LiNi_0.5Mn_1.5O₄ synthesized at 900 ℃ and 950 ℃ had cubic spinel structure with clearly defined shape. LiNi_0.5Mn_1.5O₄ spinel phase decomposed at 1 000 ℃ accompanying with structural and morphological degradation. TG measurement revealed that the weight loss during heating process could be mostly gained in cooling process, and the upward tendency of weight loss during heating process decreased, while that of irreversible weight loss rapidly increased with the increase of temperature. LiNi_0.5Mn_1.5O₄ powders prepared at 900 ℃ for 12 h delivered the maximum discharge capacity of 134 mAh·g^-1 with good cyclic performance at 2/7 C. In addition, by adjusting the calcination time at 900 ℃, the capacity and cycling performance of LiNi_0.5Mn_1.5O₄ were further enhanced.     

LiMn2O4表面包覆Li4Ti5O12的制备及倍率特性

采用固相法合成了尖晶石型LiMn₂O₄，并通过溶胶-凝胶法制备了不同物质的量的百分比含量Li₄Ti₅O₁₂包覆的正极材料。X-射线衍射和扫描电镜结果表明，Li₄Ti₅O₁₂微粒包覆在LiMn₂O₄的表面没有产生晶体结构的变化。实验电池在室温下，以1C，2C和5C倍率作充放电循环测试；结果表明，与未包覆的LiMn₂O₄相比，表面包覆Li₄Ti₅O₁₂微粒的正极材料在高倍率下具有更好的循环稳定性。     

EDTA辅助合成Li2MnSiO4/C纳米复合锂离子电池正极材料及性能

以乙二胺四乙酸（EDTA）为配位剂,采用溶胶凝胶和溶剂热法相结合的方法合成了Li₂MnSiO₄/C纳米复合正极材料。经过EDTA配位的锂锰硅前驱体在氩气中经过700℃煅烧后,产生为颗粒尺寸约为50nm的Li₂MnSiO₄/C纳米复合粉体。在0.1C=33mA·g^-1进行充放电测试时,其首次充电和放电比容量分别为223和140mAh·g^-1,第5次循环放电比容量仍为138mAh·g^-1;电流密度升至0.2C=66mA·g^-1时,在第20次循环的放电比容量仍可稳定在80mAh·g^-1左右。这些结果表明,EDTA的配位作用可抑制杂相的形成,这种分散性相对较好的纳米复合粉体Li₂MnSiO₄正极材料表现出提高的循环稳定性。     

MnO_2/NiCo_2O_4的静电自组装合成及其电化学性能

通过带负电荷的MnO2纳米片与带正电荷的Co-Ni层状双氢氧化物(LDHs)纳米片的静电自组装外加后续热处理合成了异质层状结构的MnO2/NiCo2O4复合物.采用X射线衍射(XRD)、傅里叶变换红外(FTIR)光谱、拉曼光谱、原子吸收光谱(AAS)、场发射扫描电镜(FESEM)和透射电子显微镜(TEM)对其结构和形貌进行了表征.用循环伏安(CV)、恒流充放电和电化学交流阻抗技术对其电化学性能进行了测试.研究结果表明,该方法制得的异质复合物具有多孔层状堆垛结构,这种特殊的结构不仅增大了电解液离子的接触面积,而且还为其嵌入-脱出提供了有效途径.该复合物在1 A·g-1电流密度时,-0.6-0.45 V电位窗口内的比电容达482 F·g-1,优于纯组分MnO2和NiCo2O4的电容性能.     

Magnetic diphase nanostructure of ZnFe2O4/γ-Fe2O3

Magnetic diphase nanostructures of ZnFe₂O₄/γ-Fe₂O₃ were synthesized by a solvothermal method. The formation reactions were optimized by tuning the initial molar ratios of Fe/Zn. All samples were characterized by X-ray diffraction, thermogravimetric analysis, infrared spectroscopy, and Raman spectra. It is found that when the initial molar ratio of Fe/Zn is larger than 2, a diphase magnetic nanostructure of ZnFe₂O₄/γ-Fe₂O₃ was formed, in which the presence of ZnFe₂O₄ enhanced the thermal stability of γ-Fe₂O₃. Further increasing the initial molar ratio of Fe/Zn larger than 6 destabilized the diphase nanostructure and yielded traces of secondary phase α-Fe₂O₃. The grain surfaces of diphase nanostructure exhibited a spin-glass-like structure. At room temperature, all diphase nanostructures are superparamagnetic with saturation magnetization being increased with γ-Fe₂O₃ content.     

嵌入化合物LixMn2O4的水热浸渍合成研究

本文用水热浸渍二步法合成了尖晶石型Li_xMn₂O₄微粉，并对其采用XRD，SEM， ICP， XPS和IR等进行测试。结果表明产物为单相立方晶体，粒子尺寸范围0.15-0.5 μm, Li_xMn₂O₄中X为0.96，其中锰为Mn³⁺和Mn⁴⁺混合价态存在。该液相合成Li_xMn₂O₄材料的方法尚未见报道。     

EDTA辅助合成Li_2MnSiO_4/C纳米复合锂离子电池正极材料及性能

以乙二胺四乙酸(EDTA)为配位剂,采用溶胶凝胶和溶剂热法相结合的方法合成了Li2MnSiO4/C纳米复合正极材料。经过EDTA配位的锂锰硅前驱体在氩气中经过700℃煅烧后,产生为颗粒尺寸约为50 nm的Li2MnSiO4/C纳米复合粉体。在0.1C=33mA·g-1进行充放电测试时,其首次充电和放电比容量分别为223和140 mAh·g-1,第5次循环放电比容量仍为138 mAh·g-1;电流密度升至0.2C=66 mA·g-1时,在第20次循环的放电比容量仍可稳定在80 mAh·g-1左右。这些结果表明,EDTA的配位作用可抑制杂相的形成,这种分散性相对较好的纳米复合粉体Li2MnSiO4正极材料表现出提高的循环稳定性。     

MgFe2O4纳米粉体的水热合成及其表征(英)

MgFe₂O₄ nanoparticles were hydrothermally synthesized at 150 ℃ using iron nitrate [Fe(NO₃)₃·9H₂O], magnesium nitrate [Mg(NO₃)₂·6H₂O] and sodium hydroxide (NaOH) as starting materials by carefully controlling the reaction conditions. The influences of several factors such as presence or absence of Na⁺, molar ratio of Fe³⁺ / Mg²⁺, concentration of mental ions, temperature and reaction time on resultant products were investigated in the hydrothermal process. The sample was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM), and its magnetic properties were measured using vibrating sample magnetometer (VSM).     

MgAl2O4尖晶石对锂离子电池正极材料LiMn2O4的循环性能影响研究

MgAl₂O₄ spinel doping into cathode materials LiMn₂O₄ was used to improve the cyclic performance of the cathode. X-ray analysis results showed, when MgAl₂O₄ precursors were mixed with LiMn₂O₄ and sintered at 770 ℃ for 12 hour, MgAl₂O₄-LiMn₂O₄ mulriple spinel with the same physical characteristics as pure LiMn₂O₄ were synthesized. The electro-chemical performance testing showed, comparing with pure LiMn₂O₄, the first charge-discharge capacity of doping materials somewhat reduced, but the cyclic performance improved. The mechanism for doping material was also discussed.     

Li1.02Cr0.1Mn1.9O4表面包覆的热稳定性研究

Improvement of elevated-temperature performance of Li_1.02Cr_0.1Mn_1.9O₄ cathode material by silicious surface modification was studied. The Li_1.02Cr_0.1Mn_1.9O₄ cathode material was treated by silanes coupling agent and then heated at 580 ℃ to remove organic material. The structures of the modified and unmodified Li_1.02Cr_0.1Mn_1.9O₄ were characterized by SpectraPlus, SEM and XRD. The results show that the surface layer of Li_1.02Cr_0.1Mn_1.9O₄ material is found to be rich in silicious compound. X-ray diffraction show that all the samples have perfect spinel structure. The electrochemical characterization of modified Li_1.02Cr_0.1Mn_1.9O₄ cathode material was tested. The cycle stability of charge/discharge at 55℃ is improved. The results of the charge/discharge curves show that the modified Li_1.02Cr_0.1Mn_1.9O₄ has better performance than those unmodified according to the inhibition of decline of reversible capacity of spinel Li_1.02Cr_0.1Mn_1.9O₄. Therefore, cycle performance is improved so obviously that 86.03% of the initial capacity is preserved after 100 cycles.     

尖晶石型LiMn2O4晶体结构及锂离子筛H+/Li+交换性质研究

采用密度泛函理论平面波超软赝势和广义梯度近似法对尖晶石型LiMn2O4及其锂离子筛HMn2O4的晶体结构和性质进行了从头计算。PW91泛函最为有效,Li+被H+取代后HMn2O4晶胞收缩,点阵常数从LiMn2O4的0.823 nm减小至0.799 nm,其XRD峰也相应向高角度方向明显位移。经同种格点原子的XRD分析表明,Mn、O两元素对XRD方式和强度起着决定作用。其中Li呈+1价完全离子化,可被H+彻底交换,H与周围O在等电子密度图中呈现电子云相互连接,只带有0.42个正电荷。价轨道分态密度表明,Mn-O之间强的共价键合主要归因于Mn-d和O-p在费米能级下-7.3~-1.6 eV间的轨道重叠,形成了有利于H+/Li+交换的骨架空穴隧道。阵点和空穴多面体的体积遵守如下顺序:V8a>V48f>V8b、V16c>V16d、V16c>V48f。Li+最易迁移至邻近的16c位置,碱金属离子的交换受到离子半径和作用能大小的限制。     

PtCl2-catalyzed reactions of o-alkynylanilines with ethyl propiolate and dimethyl acetylenedicarboxylate

The PtCl₂-catalyzed reactions between indoles and ethyl propiolate gave rise to mono and double addition products. The composition of the products was largely influenced by the substituents on the indoles as well as the amount of ethyl propiolate used. o-Alkynylanilines reacted with ethyl propiolate and dimethyl acetylenedicarboxylate under the catalysis of PtCl₂ to generate the corresponding 2,3-disubstituted indoles. The reaction proceeded by following a sequential cyclization/intermolecular addition pathway.     

石墨烯修饰改性制备锂离子电池LiFePO4/LiNi0.8Co0.15Al0.05O2复合正极材料及其性能

采用两步干混-球磨方法制备了石墨烯掺杂改性的锂离子电池LiFePO_4/LiNi_(0.8)Co_(0.15)Al_(0.05)O_2复合正极材料,实现LiNi_(0.8)Co_(0.15)Al_(0.05)O_2材料的高容量和高安全性。借助X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、X射线光电子能谱(XPS)以及电化学测试等表征手段对材料的晶体结构、微观形貌和电化学性能进行了较系统的研究。结果表明,石墨烯的存在实现了Li Fe PO4材料在LiNi_(0.8)Co_(0.15)Al_(0.05)O_2材料表面的完全包覆,形成致密的包覆层,进一步抑制LiNi_(0.8)Co_(0.15)Al_(0.05)O_2与电解液之间的副反应,提高活性材料利用率和循环性能。三者之间构成导电网络,加快电子渗透和传输,提高倍率性能。Li Fe PO4质量分数为20%的Li Fe PO4-Graphene/LiNi_(0.8)Co_(0.15)Al_(0.05)O_2样品具有最佳的容量性能和长循环性能,0.1C时放电容量达到202.5 m Ah·g~(-1),3C时放电容量仍然可保持在160.5 m Ah·g~(-1)。50℃在2.8~4.3 V,0.5C下循环100次后,容量保持率为91.9%,优于LiNi_(0.8)Co_(0.15)Al_(0.05)O_2和LiFePO_4/LiNi_(0.8)Co_(0.15)Al_(0.05)O_2样品的72.9%和82.0%。     

Synthesis of Mn3O4 nanoparticles by thermal decomposition of a [bis(salicylidiminato)manganese(II)] complex

The present investigation reports on the novel synthesis of Mn₃O₄ nanoparticles using thermal decomposition and their physicochemical characterization. The Mn₃O₄ nanoparticle powder has been prepared using [bis(salicylidiminato)manganese(II)] as a precursor. The effect of oleyl amine and triphenylphosphine on the particle morphology has been investigated. Transmission electron microscopy (TEM) analysis demonstrated Mn₃O₄ nanoparticles with an average diameter of about 25 nm. The structural study by X-ray diffraction (XRD) indicates that these nanoparticles have a pure tetragonal phase. The phase pure samples were characterized using X-ray photoelectron spectroscopy (XPS) for both Mn 2p and Mn 3s levels. The values of binding energies are consistent with related values reported in the literature.     

WS2/CuGa2O4复合材料的制备及其气敏性

采用共沉淀法制备了CuGa₂O₄纳米材料,并利用水热法制备了一系列WS₂/CuGa₂O₄复合材料。结合X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)等对制备的材料进行了物相组成、表面形貌以及元素价态的分析。研究了WS₂的复合量对 CuGa₂O₄材料检测乙醇气体敏感性能的影响。实验结果表明,当 WS₂与 CuGa₂O₄质量比为 1%时,该复合材料制备的传感器在室温下对 100 μL·L^-1乙醇气体表现出 345.3 的灵敏度,响应时间和恢复时间分别为 184 和 69 s,且最低检测限为 0.1μL·L^-1。