Park Min Sik
Energy Lab., Samsung Advanced Institute of Technology, Samsung Electronics, 130 Samsung-ro, Suwon, Gyeonggi-do 443-803, Republic of Korea.
Phys Chem Chem Phys. 2014 Aug 21;16(31):16798-804. doi: 10.1039/c4cp02098g.
We have studied native point defects in the layered oxides of LiNi1/3Co1/3Mn1/3O2 and Li2MnO3, the promising cathode materials for rechargeable Li-ion batteries for the application of high lithium capacity, by performing first-principles calculations. Through the calculations of formation energies for native point defects in LiNi1/3Co1/3Mn1/3O2, it was found that the Ni vacancy and the LiNi antisite are the most dominant defects, which shows a good agreement with previous experiments. Contrary to the previous experimental analysis, however, the NiLi antisite defect is not dominant, even though both Ni and Li ions have a similar ionic radius. In Li2MnO3, the LiMn antisite defect is dominant under the O-rich and Mn-poor condition. In contrast, the MnLi antisite, the Li vacancy in the Li layer, and the oxygen vacancy are dominant at the chemical potential of the boundary in equilibrium with Li2O. To enhance the migration of Li ions for achieving high power, the experimental syntheses of LiNi1/3Co1/3Mn1/3O2 under the Ni-rich condition and Li2MnO3 under O-rich and Mn-poor condition were suggested. For Li2MnO3 suffering from poor electronic conductivity, it was found that the electronic conductivity can be increased by p- and n-type extrinsic doping under the O-rich and Mn-poor condition and the chemical potential of the boundary coexisting with Li2O, respectively, without losing the Li ion conductivity.
我们通过进行第一性原理计算，研究了LiNi1/3Co1/3Mn1/3O2和Li2MnO3层状氧化物中的本征点缺陷，这两种材料是有望用于高锂容量可充电锂离子电池的阴极材料。通过计算LiNi1/3Co1/3Mn1/3O2中本征点缺陷的形成能，发现Ni空位和LiNi反位缺陷是最主要的缺陷，这与先前的实验结果吻合良好。然而，与先前的实验分析相反，尽管Ni和Li离子具有相似的离子半径，但NiLi反位缺陷并非主要缺陷。在Li2MnO3中，在富氧和贫锰条件下，LiMn反位缺陷占主导。相比之下，在与Li2O平衡的边界化学势下，MnLi反位、Li层中的Li空位和氧空位占主导。为了增强Li离子迁移以实现高功率，建议在富镍条件下对LiNi1/3Co1/3Mn1/3O2进行实验合成，并在富氧和贫锰条件下对Li2MnO3进行实验合成。对于电子导电性较差的Li2MnO3，发现在富氧和贫锰条件下以及与Li2O共存的边界化学势下，分别通过p型和n型非本征掺杂可以提高电子导电性，而不会损失Li离子导电性。
