以柠檬酸为络合剂,聚乙二醇(PEG)为表面活性剂,偏钒酸铵、乙酸锰、磷酸二氢铵、氢氧化锂为原料,采用溶胶-凝胶法合成了xLiMnPO4·y Li3V2(PO4)3锂离子电池复合正极材料。采用X射线衍射(XRD)、扫描电镜(SEM)对其晶体结构和微观形貌...以柠檬酸为络合剂,聚乙二醇(PEG)为表面活性剂,偏钒酸铵、乙酸锰、磷酸二氢铵、氢氧化锂为原料,采用溶胶-凝胶法合成了xLiMnPO4·y Li3V2(PO4)3锂离子电池复合正极材料。采用X射线衍射(XRD)、扫描电镜(SEM)对其晶体结构和微观形貌进行表征,结果表明在700℃下烧结15 h合成的3LiMnPO4·Li3V2(PO4)3为结晶良好的两相结构,颗粒粒径相对较小且分布均匀。电化学性能研究表明,3LiMnPO4·Li3V2(PO4)3在室温0.2 C倍率下首次充放电容量分别为148.2 m Ah/g和141.5 m Ah/g,循环50次后放电容量为136.7 m Ah/g。展开更多
In this work, we report a facile route for the synthesis of Li3V2(PO4)3/C cathode material via freezedrying and then calcination. The effect of calcination temperature on the electrochemical properties of the Li3V2(PO...In this work, we report a facile route for the synthesis of Li3V2(PO4)3/C cathode material via freezedrying and then calcination. The effect of calcination temperature on the electrochemical properties of the Li3V2(PO4)3/C is also investigated. When used as a lithium-ion battery cathode, the optimized Li3V2(PO4)3/C (LVP-800) through calcination at 800 ℃ exhibits a high initial charge and discharge capacity. The excellent electrochemical performance of LVP-800 is attributed to the good crystallinity and uniform morphology of the electrode material. In addition, the residual carbon can also improve the conductivity and buffer the volume expansion during the Li-ion extraction/reinsertion. Meanwhile, charge compensation also plays an important role in excellent electrochemical performance.展开更多
The formation mechanism for the equilateral triangle structure of Lia cluster is proposed. The curve of the total energy versus the interatomic distance for this structure has been calculated by using the method of Go...The formation mechanism for the equilateral triangle structure of Lia cluster is proposed. The curve of the total energy versus the interatomic distance for this structure has been calculated by using the method of Gou＇s Modified Arrangement Channel Quantum Mechanics. The result shows that the curve has a minimal energy of-22.338 60 a.u at R = 5.82 ao. The total energy of Lia when R approaches co has the value of-22.284 09 a.u. This is also the total energy of three lithium atoms dissociated from Lia. The difference value of 0.0545 08 a.u. for the above two energy values is the dissociation energy of Li3 cluster, which is also its binding energy. Therefore the binding energy per lithium atom for Lia is 0.018 169 a.u. = 0.494 eV, which is greater than the binding energy of 0.453 eV per atom for Li2 calculated in a previous work. This means that the Li3 cluster may be formed in the equilateral triangle structure of side length R = 5.82ao stably with a stronger binding from the symmetrical interaction among the three lithium atoms.展开更多
A new compound with the stone cheinical composition as Li3AlB2O6 but with a different x-ray powder diffraction pattern as reported before was synthesized and studied experimentally by M. He, Chen X Let al （J. Solid S...A new compound with the stone cheinical composition as Li3AlB2O6 but with a different x-ray powder diffraction pattern as reported before was synthesized and studied experimentally by M. He, Chen X Let al （J. Solid State Chem. 163, 369 （2002））, but there lacks first principles study on the structure of it. Using conjugant gradient （CG） molecule dynamics （MD） simulation with a full relaxation of the atomic positions and of the shape and size of the cell, the structure of Li3AlB2O6 is studied from first principles. For the density functional, the local density approximation （LDA） and the generalized gradient approximation （GGA） forms are used respectively. Both the LDA and GGA results support the experimental structure of M. He et al. The result of MD simulation using GGA agrees with the experimental result much better. The energy bands are also studied, the band gap given by LDA and GGA are 5.65 eV, 5.34eV, respectively.展开更多
文摘以柠檬酸为络合剂,聚乙二醇(PEG)为表面活性剂,偏钒酸铵、乙酸锰、磷酸二氢铵、氢氧化锂为原料,采用溶胶-凝胶法合成了xLiMnPO4·y Li3V2(PO4)3锂离子电池复合正极材料。采用X射线衍射(XRD)、扫描电镜(SEM)对其晶体结构和微观形貌进行表征,结果表明在700℃下烧结15 h合成的3LiMnPO4·Li3V2(PO4)3为结晶良好的两相结构,颗粒粒径相对较小且分布均匀。电化学性能研究表明,3LiMnPO4·Li3V2(PO4)3在室温0.2 C倍率下首次充放电容量分别为148.2 m Ah/g和141.5 m Ah/g,循环50次后放电容量为136.7 m Ah/g。
基金supported by the National Key R&D Program of China(No.2016YFB0100500)
文摘In this work, we report a facile route for the synthesis of Li3V2(PO4)3/C cathode material via freezedrying and then calcination. The effect of calcination temperature on the electrochemical properties of the Li3V2(PO4)3/C is also investigated. When used as a lithium-ion battery cathode, the optimized Li3V2(PO4)3/C (LVP-800) through calcination at 800 ℃ exhibits a high initial charge and discharge capacity. The excellent electrochemical performance of LVP-800 is attributed to the good crystallinity and uniform morphology of the electrode material. In addition, the residual carbon can also improve the conductivity and buffer the volume expansion during the Li-ion extraction/reinsertion. Meanwhile, charge compensation also plays an important role in excellent electrochemical performance.
文摘The formation mechanism for the equilateral triangle structure of Lia cluster is proposed. The curve of the total energy versus the interatomic distance for this structure has been calculated by using the method of Gou＇s Modified Arrangement Channel Quantum Mechanics. The result shows that the curve has a minimal energy of-22.338 60 a.u at R = 5.82 ao. The total energy of Lia when R approaches co has the value of-22.284 09 a.u. This is also the total energy of three lithium atoms dissociated from Lia. The difference value of 0.0545 08 a.u. for the above two energy values is the dissociation energy of Li3 cluster, which is also its binding energy. Therefore the binding energy per lithium atom for Lia is 0.018 169 a.u. = 0.494 eV, which is greater than the binding energy of 0.453 eV per atom for Li2 calculated in a previous work. This means that the Li3 cluster may be formed in the equilateral triangle structure of side length R = 5.82ao stably with a stronger binding from the symmetrical interaction among the three lithium atoms.
基金Project supported by the National Natural Science Foundation of China and CAEP （Grant No NSAF.10376021）.
文摘A new compound with the stone cheinical composition as Li3AlB2O6 but with a different x-ray powder diffraction pattern as reported before was synthesized and studied experimentally by M. He, Chen X Let al （J. Solid State Chem. 163, 369 （2002））, but there lacks first principles study on the structure of it. Using conjugant gradient （CG） molecule dynamics （MD） simulation with a full relaxation of the atomic positions and of the shape and size of the cell, the structure of Li3AlB2O6 is studied from first principles. For the density functional, the local density approximation （LDA） and the generalized gradient approximation （GGA） forms are used respectively. Both the LDA and GGA results support the experimental structure of M. He et al. The result of MD simulation using GGA agrees with the experimental result much better. The energy bands are also studied, the band gap given by LDA and GGA are 5.65 eV, 5.34eV, respectively.
