Y2O3包覆LiCo1/3Ni1/3Mn1/3O2的电化学性能

通过在硝酸钇水溶液浸渍并焙烧的简单工艺, 在LiCo1/3Ni1/3Mn1/3O2材料表面包覆了一层Y2O3. 采用X射线衍射(XRD), 扫描电子显微镜(SEM), 透射电子显微镜(TEM), 循环伏安(CV)和恒流充放电对包覆和未包覆的LiCo1/3Ni1/3Mn1/3O2进行了测试分析. 结果表明, Y2O3包覆并没有改变LiCo1/3Ni1/3Mn1/3O2的晶体结构, 只存在于LiCo1/3Ni1/3Mn1/3O2的表面; 与未包覆的材料相比, Y2O3包覆后的材料在高电位下具有更好的容量保持率和放电容量. CV测试表明, 包覆层的存在有效抑制了材料层状结构的转变及电极与电解液的负反应.     

Fe1/2Al1/2PO4催化1,2-二氯丙烷脱氯氧化制备环氧丙烷

Fe1/2Al1/2PO4催化1;2-二氯丙烷脱氯氧化制备环氧丙烷     

TiO2包覆对LiCo1/3Ni1/3Mn1/3O2材料的表面改性

为了提高材料LiCo1/3Ni1/3Mn1/3O2的循环性能, 采用浸渍-水解法对其进行TiO2包覆. 用X射线衍射(XRD)、电化学交流阻抗谱(EIS)、电感耦合等离子体发射光谱(ICP-OES)和恒流充放电测试研究包覆材料的结构和电化学性能. TiO2仅在材料表面形成包覆层, 并未改变材料的结构. TiO2包覆能提高材料LiCo1/3Ni1/3Mn1/3O2的倍率性能和循环性能, TiO2包覆后的材料在5.0C(1.0C=160 mA·g-1)下的放电容量达到0.2C下的66.0%, 而包覆前的材料在5.0C下的放电容量仅为其0.2C下的31.5%. 包覆后的材料在2.0C下循环12周后的容量没有衰减, 而未包覆的材料容量保持率仅为94.4%. EIS测试表明包覆材料性能的提高是由于循环过程中材料的界面稳定性得到了提高. 循环后材料的XRD和ICP-OES测试表明, 包覆层能提高材料LiCo1/3Ni1/3Mn1/3O2的结构稳定性.     

CoAl2O4包覆LiNi1/3Co1/3Mn1/3O2的电化学性能

通过共沉淀法制得类球形锂离子电池正极材料LiNi_1/3Co_1/3Mn_1/3O₂,并用非水相共沉法对其进行CoAl₂O₄包覆得到LNCMO(x). 采用X射线衍射（XRD）、扫描电子显微术（SEM）和透射电子显微术（TEM）测试材料的结构和观察材料形貌. 结果表明,CoAl₂O₄在材料表面形成8 nm均匀包覆层,未改变主体材料的结构. 电化学性能测试表明,1%（by mass）CoAl₂O₄包覆量的LiNi1/3Co1/3Mn1/3O2材料（LNCMO(1)）高充电电压（3.0 ~ 4.6 V,150 mA·g^-1）100周期循环放电容量保持率为93.7%（无包覆LNCMO(0)保持率为74.4%）;55 °C高温100周期循环容量保持率为77%（无包覆LNCMO(0)保持率17%）. XRD和电感耦合等离子体原子发射光谱（ICP-AES）测试表明,CoAl₂O₄包覆的LNCMO(x)材料可有效地减缓材料中Mn离子在电解液的溶解,提高材料结构稳定性和热稳定性.     

TiO2包覆对LiCo1/3Ni1/3Mn1/3O2材料的表面改性（英文）

为了提高材料LiCo1/3Ni1/3Mn1/3O2的循环性能,采用浸渍-水解法对其进行TiO2包覆.用X射线衍射（XRD）、电化学交流阻抗谱（EIS）、电感耦合等离子体发射光谱（ICP-OES）和恒流充放电测试研究包覆材料的结构和电化学性能.TiO2仅在材料表面形成包覆层,并未改变材料的结构.TiO2包覆能提高材料LiCo1/3Ni1/3Mn1/3O2的倍率性能和循环性能,TiO2包覆后的材料在5.0C（1.0C=160mA·g^-1）下的放电容量达到0.2C下的66.0%,而包覆前的材料在5.0C下的放电容量仅为其0.2C下的31.5%.包覆后的材料在2.0C下循环12周后的容量没有衰减,而未包覆的材料容量保持率仅为94.4%.EIS测试表明包覆材料性能的提高是由于循环过程中材料的界面稳定性得到了提高.循环后材料的XRD和ICP-OES测试表明,包覆层能提高材料LiCo1/3Ni1/3Mn1/3O2的结构稳定性.     

锂离子电池正极材料LiCo1/3 Ni1/3Mn1/3O2

镍钴锰三元材料作为锂二次电池正极材料是目前国内外研究热点。综述了三元材料近几年国内外的研究状况,重点介绍了LiCo1/3Ni1/3Mn1/3O2材料的结构与电化学性能的内在联系,探讨了不同制备方法及不同元素的掺杂改性对材料的影响,讨论了LiCo1/3Ni1/3Mn1/3O2正极材料的应用前景。     

固相自引发基团置换反应制备LiNi1/3Co1/3Mn1/3O2正极材料

自从2001年Ohzuku T和Makimura Y报导LiNi1/3Co1／3Mn1/3O2正极材料以来，其一直被认为是最有可能取代LiCoO2的新型锂离子二次电池正极材料之一。氢氧化物共沉淀法是最常用的一种合成LiNi1/3Co1／3Mn1/3O2材料的方法，通过混合氢氧化物共沉淀法可以获得有着均一分布且具有很高的振实密度的球形LiNi1/3Co1/3Mn1/3O2。     

锂离子电池正极材料LixNi1/3Mn1/3Co1/3O2的合成及电化学性能研究

应用以氢氧化物共沉淀为前驱体的高温固相烧结法合成L iN i1/3Mn1/3Co1/3O2正极材料,研究了沉淀温度及烧结过程锂盐投入量对该材料的结构和电化学性能的影响.结果表明,以室温(~20℃)下合成的氢氧化物为前驱体制备的L iN i1/3Mn1/3Co1/3O2具有较好的电化学性能.高温固相烧结会导致部分L iOH损失,因而在合成过程中需加入过量的氢氧化锂,实验表明L i1.08N i1/3Mn1/3Co1/3O2材料的电化学性能最优.     

xLi2MnO3·(1-x)LiNi1/3Co1/3Mn1/3O2(x=0.1、0.2、0.3和0.4)固溶体材料性能研究

通过LiNO3与Mn(NO3)2的混合溶液与LiNi1/3Co1/3Mn1/3O2粉体共混干燥后在900℃热处理12 h制备了xLi2MnO3.(1-x)LiNi1/3Co1/3Mn1/3O2(x=0.1、0.2、0.3和0.4)固溶体。随着x的增加,固溶体的XRD峰强度减弱,峰形变宽,而在20°~30°间的结构特征峰(LiMn6)更加明显;尽管固溶体的外观形貌为团聚状,但组成其的单颗粒平均粒径随着x增大,由x=0.1时的250 nm增大到x=0.4时的350 nm。随着充放电截止电压的升高,固溶体的放电比容量增大;在2.5~4.6 V间充放电,当x=0.2时,充放电的极化最小,放电平台最高;不同倍率充放电循环21周后发现随着x的增大,容量保持率从91.2%增加大105.6%。研究结果表明,Li2MnO3可以改善LiNi1/3Co1/3Mn1/3O2材料的电化学性能。     

锂离子电池正极材料LiNi1/3Co1/3Mn1/3O2的制备及其电化学性能

以Ni1/3Co1/3Mn1/3(OH)2(2)和Li2CO3为原料,在空气气氛中,经过高温热处理工艺制备了高结晶度的锂离子电池正极材料LiNi1/3Co1/3Mn1/3O2(1)。正交试验确定最佳工艺条件为:2 0.3 mol,n(Li):n(2)=1.2,于950℃反应13 h。电化学性能研究结果表明,在2.7 V～4.6 V,电流密度16 mA.g-1时,1的首次放电比容量为203.4 mAh.g-1;经16 mA.g-1循环2次,32 mA.g-1循环9次,80 mA.g-1循环20次后放电比容量为164.1 mAh.g-1。     

Structure and electrical conductivity of the ferrocuprate solid solutions Sm1/2Gd1/2BaCuFeO5.05, Gd1/2Yb1/2BaCuFeO5.02 and Ho1/3Yb2/3BaCuFeO5.05

The unit cell parameters of the crystal structures of the ferrocuprate solid solutions Sm_1/2Gd_1/2BaCuFeO_5.05, Gd_1/2Yb_1/2BaCuFeO_5.02, and Ho_1/3Yb_2/3BaCuFeO_5.05 in air in the temperature range 293–1093 K have been determined by X-ray powder diffraction, and their electrical conductivity has been studied. The structural characteristics of layered ferrocuprates are determined by the size of rare-earth cations in their structures, whereas the conductivity of ferrocuprates depends on the electronic configuration of these cations. Original Russian Text ? A.I. Klyndyuk, 2007, published in Zhurnal Neorganicheskoi Khimii, 2007, Vol. 52, No. 3, pp. 370–374.     

Syntheses and characterizations of complex perovskite oxynitrides LaMg1/3Ta2/3O2N, LaMg1/2Ta1/2O5/2N1/2, and BaSc0.05Ta0.95O2.1N0.9

The following complex oxynitride perovskites have been prepared: LaMg_1/3Ta_2/3O₂N, LaMg_1/2Ta_1/2O_5/2N_1/2, and BaSc_0.05Ta_0.95O_2.1N_0.9. Synchrotron X-ray powder diffraction analyses show that LaMg_1/3Ta_2/3O₂N and LaMg_1/2Ta_1/2O_5/2N_1/2 are isostructural to the oxide La₂Mg(Mg_1/3Ta_2/3)O₆ (space group P2₁/n), whereas BaSc_0.05Ta_0.95O_2.1N_0.9 has a simple cubic symmetry similarly to BaTaO₂N. The orderings of octahedral cations are markedly diminished in the above oxynitrides, as compared with the related oxides such as La₂Mg(Mg_1/3Ta_2/3)O₆ and Ba₂ScTaO₆. The optical band gaps are similar for the homologous compositions, LaMg_1/3Ta_2/3O₂N, LaMg_1/2Ta_1/2O_5/2N_1/2 and LaTaON₂ (1.9 eV), and BaSc_0.05Ta_0.95O_2.1N_0.9 and BaTaO₂N (1.8 eV), while the absorption edges become broader for the complex derivatives. As revealed from the impedance spectroscopic analysis, the oxynitrides have clearly different dielectric components from those of comparable oxides containing Ta⁵⁺. Impedance spectroscopy reveals interesting capacitor geometry in BaSc_0.05Ta_0.95O_2.1N_0.9 in which the semiconducting oxynitride grains are separated by insulating secondary phases. Most notably BaSc_0.05Ta_0.95O_2.1N_0.9 has a bulk component with a high relative permittivity (κ=7300) and the grain boundary component with an even higher κ.     

带有乙烯基苄基的长链季铵盐的合成及安全性研究

以对乙烯基苄基氯(C_9H_9Cl)为原料,与二甲基十六烷基胺(16DMA)合成新型季铵盐抗菌单体N,N-二甲基十四烷基对乙烯基苄基氯化铵(C_9H_9Cl-16DMA),并用FT IR、~1H NMR、EA、TG等手段表征其结构;采用抑菌圈法测试季铵盐单体对大肠杆菌、金黄色葡萄球菌和枯草芽孢杆菌的抑菌活性。通过家兔的生理特征测试、急性皮肤刺激性实验和小鼠经口毒性实验表征了该季铵盐单体对人体的安全性,毒理实验结果显示,家兔生理特征无异样变化;家兔的皮肤没有任何变化,根据寇氏法公式求出单体对小鼠的7d的LD_(50)及其95%可信限范围为3000.68(2560.57~3440.79)mg/kg。     

量子顺电体La1/2Na1/2TiO3纳米晶的制备与谱学表征

用改进硬脂酸溶胶-凝胶法制备了量子顺电体La     

Non-Condon effects in triplet-singlet spectra. The 3B1-1A1 system of NO2− in NaNO2 and NaHCO2

Spin-level resolved spectra of the ³B₁-¹A₁ (T₁-S_o) transition of NO₂^? in neat NaNO₂ and in a NaHCO₂ host at ? 4 K show different intensity envelopes for the totally symmetric bending progression, indicating a breakdown of the Condon approximation. The non-Condon effects are associated predominantly with the τ₂ spin level of the ³B₁ state and are particularly severe in NaHCO₂/NO₂^?. The results can be reasonably interpreted in terms of an empirical linear dependence of the transition moment on the bending coordinate, but the detailed origin of the effect is unclear.     

Rotational analysis of the 201 and 211 bands in the Ã2Σ+-X̃ 2Π spectrum of N2O+

Analysis of new emission spectra of òΣ⁺-X? ²Π in N₂O⁺, including the forbidden components with Δν₂ = 1, have made it possible to locate all four vibronic components of the ν″₂ = 1 manifold. Principal rotational constants and spinvibronic terms are given. A previous estimate of the Renner parameter is revised to a value of ?0.179 ± 0.002.     

Electrochemical performance of a nano SnO2-modified LiNi1/3Co1/3Mn1/3O2 cathode material

The nano SnO₂-modified LiNi_1/3Co_1/3Mn_1/3O₂ was successfully prepared by a carrier transfer method. The pristine and modified samples were characterized with various techniques such as XRD, SEM, XPS and EDS. The results showed that the SnO₂ particles did not enter the crystal structure of LiNi1/3Co1/ 3Mn1/3O₂, many nano SnO₂ particles were uniformly covered on the surface of LiNi_1/3Co_1/3Mn_1/3O₂ and the modified thin layer could inhibit the dissolution of transition metal oxides. The electrochemical tests indicated that the existence of nano SnO₂ could improve the discharge capacity and rate capability owing to the decreased interfacial polarization. The cycling stability was remarkably improved at room temperature and 55 ℃. The XRD patterns of the fresh NCM electrode and after 50 cycles proved that the structural change of NCM was not so effective on the capacity fade.     

Threshold energies for production of CH2(3B1) and CH2(1A1) from ketene photolysis. The CH2(3B1) ↔ CH2(1A1) energy splitting

By measuring the relative CO quantum yields from ketene photolysis as a function of photolysis wavelength we have determined the threshold energy at 25° for CH₂CO(¹A₁) → CH₂(³B₁) + CO(¹Σ⁺) to be 75.7 ± 1.0 kcal/mole. This corresponds to a value of 90.7 ± 1.0 kcal/mole for ΔH_f298⁰[CH₂(³B₁)]. By measuring the relative ratio of CH₂(¹A₁)/CH₂(³B₁) from ketene photolysis as a function of photolysis wavelength we have determined the threshold energy at 25°C for CH₂CO(¹A₁) → CH₂(¹A₁) + CO(¹Σ⁺) to be 84.0 ± 0.6 kcal/mole. This corresponds to a value of 99.0 ± 0.6 kcal/mole for ΔH_f298⁰[CH₂(¹A₁)]. Thus a value for the CH₂(³B₁) ? CH₂(¹A₁) energy splitting of 8.3 ± 1 kcal/mole is determined, which agrees with three other recent independent experimental estimates and the most recent quantum theoretical calculations.