Lo Wen-Tse, Yu Ching, Leggesse Ermias Girma, Nachimuthu Santhanamoorthi, Jiang Jyh-Chiang
Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan, Republic of China.
J Phys Chem Lett. 2019 Sep 5;10(17):4842-4850. doi: 10.1021/acs.jpclett.9b01516. Epub 2019 Aug 12.
Improving the stability of lithium-rich cathode materials is important in refining the overall performance of lithium-ion batteries. Here, we have proposed doping of different metal atoms such as K, Ca, Cd, and Al in different sites of LiNiMnO, and we have investigated their structural and electronic properties using first-principles calculations. We found that the Ni ions in the pristine LiNiMnO structure maintained the +3 oxidation state for a longer time and resulted in the structural deformation during the long cycling process. Whereas, the Ni ions in the Cd-, K-, and Ca-doped LiNiMnO structure are in the +3 oxidation state for a very short time, compared to the pristine system. Our density functional theory (DFT) results show that the doping of the Cd ion in the Ni site of LiNiMnO is the most suitable one, because it inhibits structural change, decreases the formation energy, and suppresses the Jahn-Teller distortion, compared with the pristine system and other dopant atoms. This theoretical study gives new insight about doping strategy and will help in improving the electrochemical performance of Li-rich cathode materials.
提高富锂正极材料的稳定性对于提升锂离子电池的整体性能至关重要。在此，我们提出在LiNiMnO的不同位点掺杂K、Ca、Cd和Al等不同金属原子，并使用第一性原理计算研究了它们的结构和电子性质。我们发现，原始LiNiMnO结构中的Ni离子在较长时间内保持+3氧化态，并在长循环过程中导致结构变形。然而，与原始体系相比，Cd、K和Ca掺杂的LiNiMnO结构中的Ni离子处于+3氧化态的时间非常短。我们的密度泛函理论（DFT）结果表明，在LiNiMnO的Ni位点掺杂Cd离子是最合适的，因为与原始体系和其他掺杂原子相比，它抑制了结构变化，降低了形成能，并抑制了 Jahn-Teller 畸变。这项理论研究为掺杂策略提供了新的见解，并将有助于提高富锂正极材料的电化学性能。
