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Jin‐Nan Zhang Ge Lin Yee‐Ping Ho Ping Li Albert H. L. Chow 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(7):907-909
The two symmetry‐independent molecules of the title compound, cevane‐3β,6α,20‐triol ethanol hydrate (2/1/1), 2C27H45NO3·C2H6O·H2O, have the same stereochemical assignments. The six‐membered rings A, B, E and F are in the chair conformation, while ring D is in a boat conformation. The ring fusions are A/Btrans, B/Ctrans, C/Dcis, D/Etrans and E/Ftrans. The verticine molecules are bridged by water and ethanol molecules via hydrogen bonds to form two‐dimensional layers, and the crystal structure is built up by stacking of these layers. 相似文献
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Shunyi Yang Xianyou Wang Quanqi Chen Xiukang Yang Jiaojiao Li Qiliang Wei 《Journal of Solid State Electrochemistry》2012,16(2):481-490
LiNi1/3Co1/3Mn1/3O2 cathode materials for the application of lithium ion batteries were synthesized by carbonate co-precipitation routine using
different ammonium salt as a complexant. The structures and morphologies of the precursor [Ni1/3Co1/3Mn1/3]CO3 and LiNi1/3Co1/3Mn1/3O2 were investigated through X-ray diffraction, scanning electron microscope, and transmission electron microscopy. The electrochemical
properties of LiNi1/3Co1/3Mn1/3O2 were examined using charge/discharge cycling and cyclic voltammogram tests. The results revealed that the microscopic structures,
particle size distribution, and the morphology properties of the precursor and electrochemical performance of LiNi1/3Co1/3Mn1/3O2 were primarily dependent on the complexant. Among all as-prepared LiNi1/3Co1/3Mn1/3O2 cathode materials, the sample prepared from Na2CO3–NH4HCO3 routine using NH4HCO3 as the complexant showed the smallest irreversible capacity of 19.5 mAh g−1 and highest discharge capacity of 178.4 mAh g−1 at the first cycle as well as stable cycling performance (98.7% of the initial capacity was retained after 50 cycles) at
0.1 C (20 mA g−1) in the voltage range of 2.5–4.4 V vs. Li+/Li. Moreover, it delivered high discharge capacity of over 135 mAh g−1 at 5 C (1,000 mA g−1). 相似文献
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Jonathan T. Reeves Daniel R. Fandrick Zhulin Tan Jinhua J. Song Nathan K. Yee Chris H. Senanayake 《Tetrahedron letters》2009,50(25):3077-5222
Several diethyl 2-cumylmalonates underwent fragmentation and dimerization in PPA at elevated temperatures to give 1,1,3-trimethyl-3-arylindanes in good yields. The same products were obtained from 2-cumylmalonic acid, ethyl 2-cumylcyanoacetate, and 2-cumyl Meldrum’s acid. This represents the first example of an SN1/E1 ionization with diethyl malonate as the leaving group. 相似文献
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A method for the separation of microgram quantities of T1/I/ and T1/III/ from hydrochloric acid solutions has been developed. T1/III/ was extracted as HTlCl4 into benzene by di-n-pentyl sulphoxide /DPSO/ and di-n-octyl sulphoxide /DOSO/. Conditions for the effective extraction of T1/III/, free from T1/I/, have been worked out. 相似文献
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通过共沉淀法与固相法相结合制备了掺锌的高稳定性Li(Ni1/3Co1/3Mn1/3)1-xZnxO2 (x=0, 0.02, 0.05)正极材料. 循环伏安(CV)曲线表明Zn掺杂使氧化峰与还原峰的电势差减小到0.09 V, 电化学阻抗谱(EIS)曲线表明Zn掺杂使电极的阻抗从266 Ω减小到102 Ω. Li+嵌入扩散系数从1.20×10-11 cm2·s-1增大到 2.54×10-11 cm2·s-1. Li(Ni1/3Co1/3Mn1/3)0.98Zn0.02O2正极材料以0.3C充放电在较高的截止电压(4.6 V)下比其他两种材料的电化学循环性能更稳定, 其第二周的放电比容量为176.2 mAh·g-1, 循环100周后容量几乎没衰减; 高温(55 °C)下充放电循环100周, 其放电比容量平均每周仅衰减0.20%, 远小于其他两种正极材料(LiNi1/3Co1/3Mn1/3O2平均每周衰减0.54%; Li(Ni1/3Co1/3Mn1/3)0.95Zn0.05O2平均每周衰减0.38%). Li(Ni1/3Co1/3Mn1/3)0.98Zn0.02O2正极材料以3C充放电时其放电比容量可达142 mAh·g-1, 高于其他两种正极材料. 电化学稳定性的提高归因于Zn掺杂后减小了电极的极化和阻抗, 增大了锂离子扩散系数. 相似文献
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TiO2包覆对LiCo1/3Ni1/3Mn1/3O2材料的表面改性 总被引:1,自引:1,他引:0
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. 相似文献
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The transition linewidth ΔE in crystal C6H6, C6D6 and sym-C6H3D3 has been measured as a function of temperature T from 4.2 to 135°K, and it extrapolates to a common value of ΔEo = 50 cm? at O°K. In C6H6 ΔE = (50 + 7T) cm?1, indicative of strong exciton—phonon coupling, and there is a line shift of +40 cm?1 per substituent deuteron. Fluorescence excitation spectral data are used to separate the 1B1u(= S2) decay rate kH = 9.4 × 1012 sec?1, derived from ΔE0, into S2S1 internal conversion (rate ≈ 6.6 × 1012 sec?1) and S2Sx (channel 3) internal conversion (rate ≈ 2.8 × 1012 sec?1. A similar value of kH = 9.9 × 1012 sec?1 is obtained from the S2So fluorescence quantum yield of liquid benzene. 相似文献
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采用高温固相合成法制备了Li[Ni(1-x)/3Mn(1-x)/3Co(1-x)/3Mox]O2 (x=0, 0.005, 0.01, 0.02). 对它们进行了XRD, SEM, 循环伏安及充放电容量测试, 结果发现, 掺杂x=0.01 Mo的样品具有较高的嵌锂容量和良好的循环稳定性, 在20 mA/g放电电流密度和2.3~4.6 V的电压范围内具有211.6 mAh/g的首次放电比容量, 循环50周后放电比容量仍能达到185.9 mAh/g, 容量损失为12.1%. 相似文献
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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。 相似文献
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层状LiCo1/3Ni1/3Mn1/3O2正极材料的合成及电化学性能研究 总被引:13,自引:0,他引:13
采用液相法在800 ℃空气中烧结20 h合成出层状LiCo1/3Ni1/3Mn1/3O2正极材料。通过XRD、IR、SEM、XPS和电化学性能测试考察了产物的组成、结构、形貌及电化学性能。结果表明,所合成的LiCo1/3Ni1/3Mn1/3O2为六方单相,层状结构发育完善;产物呈球形且粒度小,分布窄,平均粒径为0.3 μm。以1 mA·cm-2的电流密度,在2.7~4.3 V区间进行充放电测试,前4周的充放电比容量分别为168/160 mAh·g-1、169/162 mAh·g-1、165/160 mAh·g-1、163/158 mAh·g-1,循环性能优良。循环伏安实验表明,该材料在3.9 V附近出现了一对对称性好的氧化还原峰。 相似文献
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A. I. Klyndyuk 《Russian Journal of Inorganic Chemistry》2007,52(3):321-325
The unit cell parameters of the crystal structures of the ferrocuprate solid solutions Sm1/2Gd1/2BaCuFeO5.05, Gd1/2Yb1/2BaCuFeO5.02, and Ho1/3Yb2/3BaCuFeO5.05 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. 相似文献
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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. 相似文献
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利用琥珀酸为鳌合剂的湿化学法成功合成了一系列锂离子电池正极材料LiNi1/3Mn1/3Co1/3O2,在合成过程中改变琥珀酸与金属离子摩尔比(R)并研究了这一参数对合成LiNi1/3Mn1/3Co1/3O2材料物理及电化学性质的影响.采用热重、X射线衍射、Rietveld精修、扫描电镜以及超导量子干涉仪对反应机理、材料的结构、形貌以及磁学性质进行了详细表征.得到最佳合成条件为R=1,此时LiNi1/3Mn1/3Co1/3O2的阳离子混排度最低.此外,通过Rietveld精修得到该材料阳离子混排度的结果与通过磁学方法得到的结果定量相符,如对于在R=1条件下合成的样品,Rietveld精修结果显示其阳离子混排度为1.85%,而超导量子干涉仪的测试结果为1.80%.当充放电区间为3.0-4.3V,电流密度为0.2C(1C=160mA·g-1)时,该样品的首次放电容量为161mAh·g-1,库仑效率为93.1%,经过50次循环后,容量保持率可达91.3%. 相似文献
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采用碳酸盐共沉淀-高温固相法制备了一系列表面碳包覆改性(w=1.0%,2.0%,3.0%)的LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2正极材料,借助X射线衍射(XRD)分析、扫描电镜(SEM)、透射电镜(TEM)、电化学阻抗谱(EIS)和恒电流充放电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,碳成功地包覆在了材料颗粒的表面,碳包覆改性后的材料具有良好的α-Na Fe O2结构(空间群:R3m),且随着包碳量的增加,一次颗粒平均尺寸逐渐增大(从177 nm增至209 nm)。表面的无定形碳层可以提高材料的电子导电率,减少电极材料与电解液的副反应,故而碳包覆材料的电化学性能都有了一定程度提升。包覆碳量为2.0%的样品高倍率和长循环性能最好,在2.7~4.3 V,1C下循环100次后,容量保持率为93%;在0.1C、0.2C、0.5C、1C、3C、5C、10C和20C时的放电比容量分别为:155、148、145、138、127、116、104和96 m Ah·g-1。在超高倍率50C(9 A·g-1)时,其放电比容量还能达到62 m Ah·g-1(原始LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2材料仅为30 m Ah·g-1),倍率性能十分优异。 相似文献
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采用碳酸盐共沉淀-高温固相法制备了一系列表面碳包覆改性(w=1.0%,2.0%,3.0%)的LiNi1/3Co1/3Mn1/3O2正极材料,借助X射线衍射(XRD)分析、扫描电镜(SEM)、透射电镜(TEM)、电化学阻抗谱(EIS)和恒电流充放电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,碳成功地包覆在了材料颗粒的表面,碳包覆改性后的材料具有良好的α-NaFeO2结构(空间群为R3m),且随着包碳量的增加,一次颗粒平均尺寸逐渐增大(从177 nm增至209 nm)。表面的无定形碳层可以提高材料的电子导电率,减少电极材料与电解液的副反应,故而碳包覆材料的电化学性能都有了一定程度提升。包覆碳量为2.0%的样品高倍率和长循环性能最好,在2.7~4.3 V,1C下循环100次后,容量保持率为93%;在0.1C、0.2C、0.5C、1C、3C、5C、10C和20C时的放电比容量分别为:155、148、145、138、127、116、104和96 mAh·g-1。在超高倍率50C(9 A·g-1)时,其放电比容量还能达到62 mAh·g-1(原始LiNi1/3Co1/3Mn1/3O2材料仅为30 mAh·g-1),倍率性能十分优异。 相似文献
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