First-principles study of Mn antisite defect in Li₂MnO₃

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Lithium-rich layered Li2MnO3 is a promising cathode material for high-energy lithium-ion batteries.
• Intrinsic defects, such as Mn antisite defects (Mn_Li), are prevalent in Li2MnO3 due to synthesis variations.
• Understanding these defects is crucial for optimizing electrochemical properties and battery performance.

Purpose of the Study:

• To investigate the energetic and electronic properties associated with Mn antisite defects (Mn_Li) in Li2MnO3.
• To elucidate the impact of Mn_Li defects on vacancy formation and ion migration.
• To establish a clearer relationship between intrinsic defects and the electrochemical behavior of Li2MnO3.

Main Methods:

• First-principles calculations were employed to study the energetics and electronic properties of Mn_Li defects.
• Analysis of formation energies for lithium and oxygen vacancies around Mn_Li defects.
• Investigation of lithium and manganese ion migration pathways and energy barriers.

Main Results:

• Mn_Li defects reduce the formation energy of nearby lithium vacancies but increase that of oxygen vacancies, suggesting suppressed oxygen release.
• Oxygen and manganese atoms near Mn_Li contribute to charge compensation during delithiation.
• Mn_Li defects increase lithium diffusion barriers but decrease migration barriers for manganese, particularly for defect manganese ions.

Conclusions:

• Mn antisite defects play a significant role in the stability and electrochemical performance of Li2MnO3.
• The findings provide fundamental insights into defect engineering for improved cathode materials.
• This work contributes to understanding the correlation between intrinsic defects and capacity retention in Li2MnO3.