The nanocomposite films were prepared by direct intercalation of poly(ethylene oxide) and PEO into MoO 3 xerogel via sol-gel route.The electrochromic behavior and the chemical conditions of Li + ions were investigat...The nanocomposite films were prepared by direct intercalation of poly(ethylene oxide) and PEO into MoO 3 xerogel via sol-gel route.The electrochromic behavior and the chemical conditions of Li + ions were investigated by cyclic voltammograms,UV-visible spectral transmittance and XPS.The results show that the cycling efficiency and the reversibility of insertion/extraction of Li + ions in (PEO) 1MoO 3·nH 2O nanocomposite film were improved.The intercalation of PEO into MoO 3 xerogel modulated the wavelength range of electrochromism and enhanced the electrochromic efficiency.Two different chemical conditions of Li + ions existing in the interlayer and interstitial positions of MoO 3 lattice were observed in MoO 3 xerogel and (PEO) 1MoO 3·nH 2O nanocomposite films.展开更多
TiO2 is a latent anode material for rechargeable lithium batteries. Our simulation models, basing lepidocrocite and 2-MnO2 type TiO2 were investigated by density functional theory （DFT）. The key issues are focused o...TiO2 is a latent anode material for rechargeable lithium batteries. Our simulation models, basing lepidocrocite and 2-MnO2 type TiO2 were investigated by density functional theory （DFT）. The key issues are focused on the lithium insertion sites, electronic structures, and the conducting paths of Li＋ ions. Our calculated data indicate the calculated voltage of 2-MnO2 type TiO2 is higher than that of lepidocrocite type TiO2. The Li＋ ion migration energy barrier of lepidocroeite type YiO2 along the [1 0 0] direction （0.45 eV） is lower than that of along the [110] direction （0.57 eV）. The energy barriers of 2-MnO2 type TiO2 to move a Li＋ ion among the adjacent embedded sites （16c or 8a sites） is 0.68 eV.展开更多
Tin-doped multiwall carbon nanotubes (CNTs) were prepared by electrolysis in molten salt of LiCl (62%)-NaCl(37%)-SnCl2(1%) in mass fraction with a graphite rod as a cathode. TEM and XRD investigations show that struct...Tin-doped multiwall carbon nanotubes (CNTs) were prepared by electrolysis in molten salt of LiCl (62%)-NaCl(37%)-SnCl2(1%) in mass fraction with a graphite rod as a cathode. TEM and XRD investigations show that structure characteristic of tin-doped CNTs is webs of well-graphitized hollow tubes with outer diameters between 10 and 20 nm with presence of Sn and SnO2. The EDS elementary analysis confirms the content of tin in the products was 9%. Electrochemical Li insertion into the doped CNTs was investigated in a nonaqueous medium. Galvanostatic discharge-charge measurement revealed that their specific capacities of insertion and extraction lithium were 1762mAh/g and 1295mAh/g, respectively, in the first cycle with almost coulomb efficiency of 73%. The coulomb efficiency increased to more than 90% after the ninth cycle, and the reversible capacity was about 210 mAh/g.展开更多
锂离子电池负极材料钛酸锂由于其高功率和优异的循环性能得到了广泛的研究,但是较低的比容量(175 m Ah/g)限制了其应用前景。与钛酸锂相比,铌基氧化物具有相似的嵌脱锂电位和更高的比容量,也展现出良好的倍率性能和循环性能,有望成为新...锂离子电池负极材料钛酸锂由于其高功率和优异的循环性能得到了广泛的研究,但是较低的比容量(175 m Ah/g)限制了其应用前景。与钛酸锂相比,铌基氧化物具有相似的嵌脱锂电位和更高的比容量,也展现出良好的倍率性能和循环性能,有望成为新型功率型负极材料。本文综述了多种铌基复合金属氧化物(Nb2O5,Ti Nb2O7,Li Nb3O8等)的晶体结构、电化学性能和嵌脱锂机理,讨论了材料的组成、形貌和制备工艺等对其嵌脱锂性能的影响,并概述其作用机制。此外,本文还归纳总结了铌基材料嵌脱锂行为的共性,并比较了它们与钛酸锂的异同,对其作为高功率锂离子电池负极材料的研究趋势和发展前景进行了展望。展开更多
采用基于密度泛函理论的第一性原理平面波赝势方法,计算不同数量的锂离子引起的硅材料晶体结构的变化以及在嵌锂过程中形成Li x Si(x=1、2、2.4、4.4)合金相的形成能与电子结构.采用LST/QST方法计算过渡态,模拟合金体相中的锂离子迁移过...采用基于密度泛函理论的第一性原理平面波赝势方法,计算不同数量的锂离子引起的硅材料晶体结构的变化以及在嵌锂过程中形成Li x Si(x=1、2、2.4、4.4)合金相的形成能与电子结构.采用LST/QST方法计算过渡态,模拟合金体相中的锂离子迁移过程.计算结果表明,随着嵌锂数量的增加,硅晶胞的体积在不断增大;Li_(x) Si合金相的形成能为负值,表明在嵌锂过程中锂离子和硅原子可以自发形成这些合金相,其中Li _(7) Si _(3)合金最容易形成;随着嵌锂量的增加,锂离子在费米能级处s轨道提供的电子数逐渐增加,锂硅合金在费米能级处的电子数量呈增大趋势,表明锂硅合金的导电性越来越优;常温下Li_(2)Si体相中很难直接形成锂离子空位,但锂离子空位的迁移过程很容易发生.展开更多
文摘The nanocomposite films were prepared by direct intercalation of poly(ethylene oxide) and PEO into MoO 3 xerogel via sol-gel route.The electrochromic behavior and the chemical conditions of Li + ions were investigated by cyclic voltammograms,UV-visible spectral transmittance and XPS.The results show that the cycling efficiency and the reversibility of insertion/extraction of Li + ions in (PEO) 1MoO 3·nH 2O nanocomposite film were improved.The intercalation of PEO into MoO 3 xerogel modulated the wavelength range of electrochromism and enhanced the electrochromic efficiency.Two different chemical conditions of Li + ions existing in the interlayer and interstitial positions of MoO 3 lattice were observed in MoO 3 xerogel and (PEO) 1MoO 3·nH 2O nanocomposite films.
基金Acknowledgement This work was financially supported by the Major Program of the Natural Science Foundation of China （Grant No. 51090380）, the National Science Foundation for Distinguished Young Scholars of China （Grant No. 51125018）, the Knowledge Innovation Program of the Chinese Academy of Sciences （KGCX2-YW-214） and the special funds of ＂Mountain Tai Scholar＂ construction project. The computing platform was supported by the Computer Facility for Theoretical and Computational Chemistry, Institute of Chemistry （CFCC）, Chinese Academy of Sciences （CAS）.
文摘TiO2 is a latent anode material for rechargeable lithium batteries. Our simulation models, basing lepidocrocite and 2-MnO2 type TiO2 were investigated by density functional theory （DFT）. The key issues are focused on the lithium insertion sites, electronic structures, and the conducting paths of Li＋ ions. Our calculated data indicate the calculated voltage of 2-MnO2 type TiO2 is higher than that of lepidocrocite type TiO2. The Li＋ ion migration energy barrier of lepidocroeite type YiO2 along the [1 0 0] direction （0.45 eV） is lower than that of along the [110] direction （0.57 eV）. The energy barriers of 2-MnO2 type TiO2 to move a Li＋ ion among the adjacent embedded sites （16c or 8a sites） is 0.68 eV.
文摘Tin-doped multiwall carbon nanotubes (CNTs) were prepared by electrolysis in molten salt of LiCl (62%)-NaCl(37%)-SnCl2(1%) in mass fraction with a graphite rod as a cathode. TEM and XRD investigations show that structure characteristic of tin-doped CNTs is webs of well-graphitized hollow tubes with outer diameters between 10 and 20 nm with presence of Sn and SnO2. The EDS elementary analysis confirms the content of tin in the products was 9%. Electrochemical Li insertion into the doped CNTs was investigated in a nonaqueous medium. Galvanostatic discharge-charge measurement revealed that their specific capacities of insertion and extraction lithium were 1762mAh/g and 1295mAh/g, respectively, in the first cycle with almost coulomb efficiency of 73%. The coulomb efficiency increased to more than 90% after the ninth cycle, and the reversible capacity was about 210 mAh/g.
文摘锂离子电池负极材料钛酸锂由于其高功率和优异的循环性能得到了广泛的研究,但是较低的比容量(175 m Ah/g)限制了其应用前景。与钛酸锂相比,铌基氧化物具有相似的嵌脱锂电位和更高的比容量,也展现出良好的倍率性能和循环性能,有望成为新型功率型负极材料。本文综述了多种铌基复合金属氧化物(Nb2O5,Ti Nb2O7,Li Nb3O8等)的晶体结构、电化学性能和嵌脱锂机理,讨论了材料的组成、形貌和制备工艺等对其嵌脱锂性能的影响,并概述其作用机制。此外,本文还归纳总结了铌基材料嵌脱锂行为的共性,并比较了它们与钛酸锂的异同,对其作为高功率锂离子电池负极材料的研究趋势和发展前景进行了展望。
文摘采用基于密度泛函理论的第一性原理平面波赝势方法,计算不同数量的锂离子引起的硅材料晶体结构的变化以及在嵌锂过程中形成Li x Si(x=1、2、2.4、4.4)合金相的形成能与电子结构.采用LST/QST方法计算过渡态,模拟合金体相中的锂离子迁移过程.计算结果表明,随着嵌锂数量的增加,硅晶胞的体积在不断增大;Li_(x) Si合金相的形成能为负值,表明在嵌锂过程中锂离子和硅原子可以自发形成这些合金相,其中Li _(7) Si _(3)合金最容易形成;随着嵌锂量的增加,锂离子在费米能级处s轨道提供的电子数逐渐增加,锂硅合金在费米能级处的电子数量呈增大趋势,表明锂硅合金的导电性越来越优;常温下Li_(2)Si体相中很难直接形成锂离子空位,但锂离子空位的迁移过程很容易发生.
