Comparison of Small Polaron Migration and Phase Separation in Olivine LiMnPO₄ and LiFePO₄ using Hybrid Density Functional Theory
Comparison of Small Polaron Migration and Phase Separation in Olivine LiMnPO₄ and LiFePO₄ using Hybrid Density Functional Theory
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DOI：
10.1103/physrevb.83.075112
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发表时间：
2011-02
期刊：
影响因子：
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通讯作者：
S. Ong;V. Chevrier;G. Ceder
中科院分区：
文献类型：
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作者：
S. Ong;V. Chevrier;G. Ceder
使用混合密度泛函理论的基础上的海德-Scuseria-Ernzerhof（HSE 06）功能，我们比较了极化子迁移和相分离的橄榄石LiMnPO 4的LiFePO 4。自由空穴和电子极化子迁移的障碍在锰橄榄石系统计算为303和196毫电子伏，分别显着高于相应的障碍170和133毫电子伏，分别为铁橄榄石系统，与以前的实验结果一致。这些结果表明，在室温下，LiMnPO 4和MnPO 4的电子电导率比它们各自的Fe类似物低约177和11倍。在锂空位或离子的存在下，发现Mn橄榄石中空穴和电子极化子迁移的势垒高出约100 - 120 meV。的HSE 06功能，其更普遍的治疗自我相互作用的错误，被认为是必不可少的适当的本地化的极化子在锰橄榄石，但预测定性不正确的相分离行为在LixFePO 4系统。
Using hybrid density functional theory based on the Heyd-Scuseria-Ernzerhof (HSE06) functional, we compared polaron migration and phase separation in olivine LiMnPO4 to LiFePO4. The barriers for free hole and electron polaron migration in the Mn olivine system are calculated to be 303 and 196 meV, respectively, significantly higher than the corresponding barriers of 170 and 133 meV, respectively, for the Fe olivine system, in agreement with previous experimental findings. These results suggest that the electronic conductivities of LiMnPO4 and MnPO4 are about 177 and 11 times lower than their respective Fe analogs at room temperature. In the presence of lithium vacancies or ions, the barriers for both hole and electron polaron migration were found to be about 100‐120 meV higher in the Mn olivine. The HSE06 functional, with its more universal treatment of self-interaction error, was found to be essential to the proper localization of a polaron in the Mn olivine but predicted qualitatively incorrect phase separation behavior in the LixFePO4 system.