Defect Chemistry and Li-ion Diffusion in Li₂RuO₃.

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Layered lithium ruthenium oxide (Li₂RuO₃) is a promising cathode material for lithium-ion batteries due to its anionic redox activity and high capacity.
• Understanding intrinsic defects and ion diffusion is crucial for optimizing Li₂RuO₃ performance.

Purpose of the Study:

• To investigate intrinsic defects, dopant effects, and lithium ion diffusion pathways in Li₂RuO₃ using atomistic simulations.
• To identify optimal trivalent dopants for enhancing lithium concentration in Li₂RuO₃.

Main Methods:

• Atomistic scale simulations were employed to calculate defect formation energies and migration barriers.
• Calculations focused on intrinsic defects (e.g., Li Frenkel, cation anti-site) and lithium diffusion paths.
• The impact of various trivalent dopants (Al³⁺, Co³⁺, Sc³⁺, In³⁺, Y³⁺, Gd³⁺, La³⁺) was assessed.

Main Results:

• The Li Frenkel defect was identified as the most favorable intrinsic defect.
• Cation anti-site defects (Li/Ru exchange) are predicted at high temperatures (1.89 eV/defect).
• The most efficient lithium diffusion pathway occurs along the ab plane with a low activation energy of 0.73 eV.
• Al³⁺ and Co³⁺ were identified as ideal trivalent dopants for increasing lithium concentration.

Conclusions:

• Atomistic simulations provide critical insights into defect chemistry and ion transport in Li₂RuO₃.
• Al³⁺ and Co³⁺ doping are recommended for enhancing the electrochemical performance of Li₂RuO₃ cathodes.
• These findings align with experimental observations, particularly for Co³⁺ doping.