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From first principle calculations, we demonstrate that LiXS_2(X = Ga, In) compounds have potential applications as cathode materials for Li ion batteries. It is shown that Li can be extracted from the LiXS_2 lattice with relatively small volume change and the XS_4 tetrahedron structure framework remains stable upon delithiation. The theoretical capacity and average intercalation potential of the LiGaS_2(LiInS_2) cathode are 190.4(144._2) m Ah/g and 3.50 V(3.53 V). The electronic structures of the LiXS_2 are insulating with band gaps of _2.88 eV and 1.99 eV for X = Ga and In, respectively.However, Li vacancies, which are formed through delithiation, change the electronic structure substantially from insulating to metallic structure, indicating that the electrical conductivities of the LiXS_2 compounds should be good during cycling.Li ion migration energy barriers are also calculated, and the results show that Li ion diffusions in the LiXS_2 compounds can be as good as those in the currently widely used electrode materials. 相似文献
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利用脉冲激光沉积法,在氧气氛下(氧分压为20 Pa)以硅为基体制备了ZnO:Al透明导电膜.靶材选用(ZnO)1-x(Al2O3)x陶瓷靶,沉积过程中基体温度保持在600℃.通过对膜进行霍尔效应测量及SEM、XRD测试分析,研究了靶材中的化学配比(掺杂比)对膜的电学特性的影响.结果表明:掺杂比影响着膜的电学性能和膜的结晶状况.掺杂铝的质量分数为1.37%时所获得的ZnO薄膜具有最小的电阻率. 相似文献
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The spinel-type LiMn$_{2}$O$_{4}$ is a promising candidate as cathode material for rechargeable Li-ion batteries due to its good thermal stability and safety. Experimentally, it is observed that in this compound there occur the structural phase transitions from cubic ($Fd\bar{3}m)$ to tetragonal ($I4_{1}/{amd}$) phase at slightly below room temperature. To understand the phase transition mechanism, we compare the Gibbs free energy between cubic phase and tetragonal phase by including the configurational entropy. Our results show that the configurational entropy contributes substantially to the stability of the cubic phase at room temperature due to the disordered Mn$^{3+}$/Mn$^{4+}$ distribution as well as the orientation of the Jahn-Teller elongation of the Mn$^{3+}$O$_{6}$ octahedron in the the spinel phase. Meanwhile, the phase transition temperature is predicted to be 267.8 K, which is comparable to the experimentally observed temperature. These results serve as a good complement to the experimental study, and are beneficial to the improving of the electrochemical performance of LiMn$_{2}$O$_{4}$ cathode. 相似文献
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The physics of ionic and electrical conduction at electrode materials of lithium-ion batteries(LIBs) are briefly summarized here, besides, we review the current research on ionic and electrical conduction in electrode material incorporating experimental and simulation studies. Commercial LIBs have been widely used in portable electronic devices and are now developed for large-scale applications in hybrid electric vehicles(HEV) and stationary distributed power stations. However,due to the physical limits of the materials, the overall performance of today's LIBs does not meet all the requirements for future applications, and the transport problem has been one of the main barriers to further improvement. The electron and Li-ion transport behaviors are important in determining the rate capacity of LIBs. 相似文献
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以福建农林大学海峡联合学院为例,将生态规划的理论及方法应用于校园规划研究,从物种的保护、土地的利用、校园多层次空间营造,校园景观廊道和生态公园的建设等方面进行剖析,力求在校园规划和建设中彰显校园功能、景观和生态的协调统一. 相似文献
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为提升传统民居光环境品质,对福清城区岑兜村代表性传统民居进行实测,结果表明该民居大部分室内的采光性能不满足设计标准需求.利用参数化模拟工具对传统民居的光环境建立数字模型进行分析,分别从玻璃透射率、室内反射比、增设内墙开窗和顶部采光口进行单项优化,得出均满足不了采光需求的结论.进而在对整体建筑风貌影响最小化的前提下,提出综合优化设计策略以改善民居室内光环境,为地方传统民居改造更新提供借鉴. 相似文献
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锗烷因其合适的带隙、较高的电子迁移速率、较好的环境稳定性、较小的电噪声和超薄的几何结构,有望取代现有硅基或锗基材料成为下一代半导体器件的理想载体.基于密度泛函理论和非平衡格林函数的第一性原理方法,研究了不同构型和浓度的氢空位簇对锗烷电子结构及锗烷中四硫富瓦烯(tetrathiafulvalene,TTF)分子掺杂性能的影响.计算结果表明,不同构型氢空位簇的引入可诱导Germanane Dehydrogenated-x H (GD–xH)体系产生不同性质的磁性,且磁矩大小亦与Lieb定理的预测结果相符,并能在GD-x H (x=1, 4, 6)体系自旋向下的能带结构中实现由缺陷态引起的类p型半导体掺杂效应,其电子激发所需的能量则会随着体系脱氢浓度的升高而不断降低.吸附TTF分子后, G/TTF和GD-xH/TTF (x=1, 2, 6)体系表现出分子掺杂效应,且GD-x H/TTF (x=1, 6)体系因分子轨道与缺陷态的杂化作用,可在自旋向上与自旋向下的能带结构中形成不同的掺杂类型.进一步的量子输运计算还表明, Armchair和Zigzag... 相似文献