锂离子电池负极材料Li2MgSi的Li脱嵌性质研究

使用基于平面波展开的第一原理赝势法,研究了锂离子电池负极材料Li2MgSi在各种脱锂量下的锂脱嵌形成能、相应的体积变化、能带结构、电子态密度以及电荷密度分布.计算结果表明:脱锂量越大需要的能量越大,随脱锂量的变化,平均一个锂的脱嵌形成能在-1.21～-1.61 eV之间.脱锂过程中,体积先膨胀后收缩,整个过程中体积变化很大,是导致材料循环性能较差的重要原因.在脱锂过程中材料显示了由半导体性到金属性又到半导体性的特征.

Lithium Extraction Properties in Anode Material Li2MgSi for Lithium Ion Batteries

The ab initio pseudopotential method with the plane wave expansion of the crystal wavefunction is employed to study the anode material Li2 MgSi for lithium ion batteries. The lithium deintercalation formation energies and the corresponding changes of crystal volumes under various amounts of lithium deintercalations are presented. The energy band structures and the electronic density of states and the charge densities for the lithium extractions in Li2MgSi are also discussed. The calculation results show that the more extractions of Li the more energies it needs. The deintercalation formation energies per lithium are between - 1.21 eV to - 1.61 eV for different amount of lithium extractions. The volume first expands then shrinks and the changes of volume are very big during the whole process. That is the important cause of bad cycle performance. And the material changes from semiconducting to metallic then to semiconducting crystal.