### Al掺杂的锂离子电池层状正极材料Li(Li0.17Ni0.17Al0.04Fe0.13Mn0.49)O2结构稳定性及氧离子氧化的理论研究

1. 内蒙古科技大学 材料与冶金学院 包头 014010
• 投稿日期:2021-04-26 发布日期:2021-07-27
• 通讯作者: 贾桂霄
• 基金资助:
项目受内蒙古自然科学基金(2021MS02003)

### Theoretical Study on the Structural Stability and Oxygen Ion Oxidation of Al-doped Lithium-ion Battery Layered Cathode Li(Li0.17Ni0.17Al0.04Fe0.13Mn0.49)O2

Kai Qiu, Mingxia Yan, Shouwang Zhao, Shengli An, Wei Wang, Guixiao Jia()

1. School of Materials and Metallurgy, Inner Mongolia University of Science and Technology, Baotou 014010, China
• Received:2021-04-26 Published:2021-07-27
• Contact: Guixiao Jia
• Supported by:
Inner Mongolia Natural Science Foundation(2021MS02003)

In lithium-ion battery, lithium rich layered transition metal oxides materials are the next generation of lithium ion cathode materials with high practical specific capacity. The specific capacity and structural stability of cathode materials are two important factors. In order to improve the overall performance of batteries, some strategies such as chemical modifications, surface coating and material composite are used. Among them element doping is an effectively method to improve the electrochemical stability of lithium-rich cathode materials. Li(Li0.17Ni0.17Al0.04Fe0.13Mn0.49)O2 (LNAFMO) as a layered cobalt-free cathode material was selected as the research object. Geometrical structures including the lattice parameters, M―O bond length (where M stands for transition metal) and O―O bond length, electronic structures including oxidation processes of transition metal and oxygen ion, oxygen release enthalpies, delithium formation energies, delithium voltage and the effect of doping element Al are investigated by a GGA (generalized gradient approximation)+U (Hubbard U value) method. Calculated results show that Ni2+ ions in the LNAFMO system are first oxidized, then Fe3+ and finally O2- during the charging. Oxygen ions with linear Al-O-Li configurations in the LNAFMO system participate in charge compensation besides those with linear Li-O-Li and Fe-O-Li configurations, different from the Li(Li0.17Ni0.17Fe0.17Mn0.49)O2 (LNFMO) system without Al doping. The doping of Al can suppress the release of oxygen, improving the structural stability of the system and the cycling performance of the battery. The doping of Al increases the special capacity of LNFMO system (246 mAh•g-1), in which the contribution of Ni/Fe transition metal and oxygen ions to the capacity is equal. The internal mechanism between the oxidation of transition metals and oxygen ions and the geometrical structures in the system has been revealed from a microscopic perspective. This work would provide a theoretical basis for the design of a low cost, high energy density and high cycle performance lithium-ion battery cathode material.