Ahn Seryung, Kim Jiyeon, Kim Bongjae, Kim Sooran
Department of Physics, Kyungpook National University, Daegu 41566, South Korea.
Department of Physics Education, Kyungpook National University, Daegu 41566, South Korea.
Phys Chem Chem Phys. 2023 Oct 18;25(40):27848-27853. doi: 10.1039/d3cp02998k.
Li-ion conductivity is one of the essential properties that influences the performance of cathode materials for Li-ion batteries. Here, using density functional theory, we investigate the polaron stability and its effect on the Li-ion diffusion in layered LiCoO with various magnetic orderings. We show that the local magnetism promotes the localized Co polaron with the Li-diffusion barrier of ∼0.34 eV. While the Li-ion diffuses, the polaron migrates in the opposite direction to the Li movement. In the non-magnetic structure, on the other hand, the polaron does not form, and the Li diffusion barrier is lowered to 0.21 eV. Although the presence of the polaron raises the diffusion barrier, the magnetically ordered structures are energetically more stable during the migration than the non-magnetic case. Thus, our work advocates the hole polaron migration scenario for Li-ion diffusion. We further demonstrate that the strong electron correlation of Co ions plays an essential role in stabilizing the Co polaron.
锂离子电导率是影响锂离子电池阴极材料性能的关键特性之一。在此，我们运用密度泛函理论，研究了具有各种磁有序的层状LiCoO中极化子的稳定性及其对锂离子扩散的影响。我们发现，局域磁性促进了局域化的Co极化子的形成，其锂离子扩散势垒约为0.34 eV。当锂离子扩散时，极化子向与锂移动相反的方向迁移。另一方面，在非磁性结构中，极化子不会形成，锂离子扩散势垒降低至0.21 eV。尽管极化子的存在提高了扩散势垒，但磁有序结构在迁移过程中的能量比非磁性情况更稳定。因此，我们的工作支持了锂离子扩散的空穴极化子迁移模式。我们进一步证明，Co离子的强电子相关性在稳定Co极化子方面起着至关重要的作用。
