Chem. J. Chinese Universities ›› 2024, Vol. 45 ›› Issue (5): 20240035.doi: 10.7503/cjcu20240035

• Physical Chemistry • Previous Articles     Next Articles

Oxygen Framework Mechanism of Layered Lithium-rich Manganese-based Materials Stabilized by High-valent Element Mo Based on First-principles Calculations

ZHANG Shuo1, ZHAO Liuyang1, HUANG Hao1(), WU Aimin1, LI Aikui2   

  1. 1.School of Materials Science and Engineering
    2.School of Electrical Engineering,Dalian University of Technology,Dalian 116024,China
  • Received:2024-01-19 Online:2024-05-10 Published:2024-03-18
  • Contact: HUANG Hao E-mail:huanghao@dlut.edu.cn
  • Supported by:
    the Five-year Action Plan for Basic Scientific Research of Shaanxi Coal-Qingling, China(SMYJY202400012C)

Abstract:

Density functional theory(DFT) first-principles calculations were employed to elucidate the stabilization mechanism of lithium-rich manganese-based materials through Mo substitution for Mn. Mo doping mitigated the volume change rate, decreasing it from ‒2.95% to ‒0.53% and improved lattice distortion both before and after lithiation. Results from vacancy formation energy and Bader charge analysis revealed a marked increase in the formation energy of seven oxygen vacancies, and the average Bader charge of the first-coordination oxygen escalated from 1.13 e to 1.18 e, which effectively suppressed unstable oxygen precipitation. The change in Bader charge of oxygen atoms before and after lithiation decreased from 0.51 e to 0.11 e, which was indicative of the robust stability of the oxygen framework during cycling. Differential charge density calculations illustrated that Mo can compensate for charge after the removal of Li. Furthermore, Mo doping enhanced lithium ion migration rates, reducing the minimum barrier from 0.55 eV to 0.42 eV. This study provides a rigorous theoretical foundation for the doping of high-valence elements in lithium-ion battery cathode materials.

Key words: Lithium-ion battery, Lithium-rich cathode material, Electronic property, Lattice oxygen, Density functional theory

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