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arXiv 1301.7207cond-mat.mtrl-sci
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LixNi0.5Mn 1.5O 4(0 <= x <= 1)相和结构的热力学第一性原理计算

Thermodynamic Analysis Using First-Principles Calculations of Phases and Structures of LixNi0.5Mn1.5O4(0 <= x <= 1)

Ippei Kishida, Kengo Orita, Atsutomo Nakamura, Yoshiyuki Yokogawa

摘要:

LiNi 0. 5Mn 1. 5O 4具有尖晶石骨架结构,是下一代高能量密度锂离子电池正极材料的理想选择。采用广义梯度近似下的投影缀加波方法,通过第一性原理计算研究了LixNi 0.5Mn 1.5O 4(0 <= x <= 1)的结构转变.我们计算了所有独特的锂网站占领配置在一个单位电池,以获得总能量和最稳定的结构,为各种组合物。热力学分析表明,当0 < x < 1时,Li_(0.5)Ni_(0.5)Mn_(1.5)O_4(x = 0.5)是唯一的稳定相。对于0 < x < 0.5,分解能低于0.1 eV,但对于0.5 < x < 1,分解能明显较高。分解能在x = 0.75时达到0.39 eV。室温下的结构的比率是由玻尔兹曼因子通过使用结构之间的能量差计算的。晶胞的晶体结构从x = 0到0.5逐渐变化,但从x = 0.5到1变化显著。该第一原理研究提供了晶体结构随本体材料的组成的变化的一般评价,其影响电极的可循环性。

英文摘要:

LiNi0.5Mn1.5O4, which has a spinel framework structure, is a promising candidate for the cathode material of next-generation lithium-ion batteries with high energy density. We investigate the structural transition in LixNi0.5Mn1.5O4 (0 <= x <= 1) through first-principles calculations using the projector augmented wave method with the generalized gradient approximation. We calculate all the unique Li-site occupation configurations in a unit cell to obtain the total energies and the most stable structures for various compositions. Thermodynamic analysis shows that Li0.5Ni0.5Mn1.5O4 with x = 0.5 is the only stable phase for 0 < x < 1. The decomposition energy is lower than 0.1 eV for 0 < x < 0.5, but is distinctly higher for 0.5 < x < 1. The decomposition energy reaches 0.39 eV at x = 0.75. The ratios of the structures at room temperature are calculated from Boltzmann factors by using the energy differences between structures. The crystal structure of the unit cell changes gradually from x = 0 to 0.5, but changes markedly from x = 0.5 to 1. This first-principles study provides a general evaluation of the variation in the crystal structure with the composition of the bulk material, which affects the cyclability of the electrode.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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