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新型锂离子电池正极材料Li0.86V0.8O2的水热合成及性质 总被引:1,自引:1,他引:0
采用两步反应制备了新型锂离子电池正极材料Li0.86V0.8O2. 该材料具有六方层状结构, 空间群为R3m. 研究了在水热条件下溶液的碱度对于钒酸锂盐形成的影响, 在低碱度的条件下, 前驱体V2O3和LiOH·H2O并未发生反应, 只有在碱度达到2.5 mol/L时, 才能形成单相的Li0.86V0.8O2材料. X射线光电子能谱分析发现, V2p的结合能位于516.4 和523.1 eV, 分别对应于四价钒离子的V2p3/2 和V2p1/2, 这说明在Li0.86V0.8O2中V离子主要价位为+4价. 在电流密度为7.4 mA/g的充放电中, Li0.86V0.8O2初始充电容量达到163 mA·h/g, 首次放电容量也能达到113 mA·h/g, 20次循环后放电容量仍然可以达到80 mA·h/g, 表现出较好的循环性能. 相似文献
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采用平面波赝势方法对菱铁矿FeCO3高压下的晶体结构, 电子构型和电子结构进行了第一性原理计算研究. 研究过程中考虑了菱铁矿FeCO3真实的反铁磁(AFM) 自旋有序态, 模拟静水压环境, 从零压逐步加压到500 GPa. 在40---50 GPa压力范围内, FeCO3发生了从高自旋(HS) AFM态到低自旋(LS) 非磁性(NM) 态的磁性相变, 伴随着晶胞体积坍塌10.5%. FeCO3在相变前后均是绝缘体, 但是相变后的LS-NM态的Fe2+ 离子的3d电子局域化程度更强, 能隙随着压力的进一步增大而逐步增大, 离化程度更高, 直到500 GPa没有发生金属绝缘体相变. 相似文献
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Phase Transition Behavior of LiCr 0.35 Mn0.65O2 under High Pressure by Electrical Conductivity Measurement 下载免费PDF全文
The electrical conductivity of powdered LiCr 0.35 Mn0.65O2 is measured under high pressure up to 26.22 GPa in the temperature range 300-413 K by using a diamond anvil cell. It is found that both conductivity and activation enthalpy change discontinuously at 5.36 GPa and 21.66 GPa. In the pressure range 1.10-5.36 GPa, pressure increases the activation enthalpy and reduces the carrier scattering, which finally leads to the conductivity increase. In the pressure ranges 6.32-21.66 GPa and 22.60-26.22 GPa, the activation enthalpy decreases with pressure increasing, which has a positive contribution to electrical conductivity increase. Two pressure-induced structural phase transitions are found by in-situ x-ray diffraction under high pressure, which results in the discontinuous changes of conductivity and activation enthalpy. 相似文献
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用二维异核多量子化学位移相关谱1H-13C HMQC,HMBC和二维同核NOESY谱研究了两个新合成的双钨核有机硒化合物的结构,归属了该化合物的1H,13C NMR谱线. 相似文献
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Comprehensive first-principles calculations are performed to provide insight into the intriguing physical properties of the ternary cubic fluoride KCrF3. The electronic structures exhibit a prominent dependence on the effective local Coulomb interaction parameter Ueff. The ground state of the cubic phase is a ferromagnetic (FM) half-metal with Ueff equal to 0, 2, and 4 eV, whereas the insulating A-type antiferromagnetic (A-AFM) state with concomitant homogeneous orbital ordering is more robust than the FM state for Ueff exceeding 4 eV. We propose that the origin of the orbital ordering is purely electronic when the cooperative Jahn-Teller distortions are absent in cubic KCrF3. 相似文献