Intrinsic Correlation between Defects, Structure, and Lithium-Ion Transport Kinetics in Epitaxial LiNi_1/3Mn_1/3Co_1/3O₂...

Area of Science:

• Materials Science
• Electrochemistry
• Solid-state Chemistry

Background:

• Lithium nickel manganese cobalt oxide (LiNi M Mn Co O ) (NMC) is a crucial cathode material for lithium-ion batteries.
• Understanding the relationship between crystallographic orientation, defects, and electrochemical performance is vital for developing advanced battery materials.

Purpose of the Study:

• To investigate the impact of crystallographic orientation and defect types on the electrochemical behavior and lithium-ion transport kinetics of epitaxial NMC thin films.
• To establish structure-property correlations for optimizing NMC cathode performance.

Main Methods:

• Pulsed laser deposition (PLD) was used to prepare epitaxial NMC thin films with controlled crystallographic orientations.
• Electrochemical testing (charge/discharge rates from C/10 to 6 C) was performed to evaluate battery performance.
• Analysis of interfaces and local crystal structure identified defect types such as antiphase boundaries (APBs) and twinned domains.

Main Results:

• NMC thin films primarily grow along the (104) and (003) planes, driven by surface energy minimization.
• Optimal lithium-ion diffusion was observed in ≈15 nm thick films with (100)-oriented growth.
• (104)- and (1̅08)-oriented NMC films with twinned microstructures demonstrated stable cycling, high capacities (141.2–149.4 mAh g ) and diffusion coefficients (7.45–7.95 × 10 cm s ).
• Films with less favorable orientations ((003), (1 0 16)) showed lower diffusion coefficients, higher APB density, and performance degradation at higher rates, except for the (104) orientation.

Conclusions:

• Crystallographic orientation and microstructure significantly influence the electrochemical performance of epitaxial NMC thin films.
• Twinned microstructures and specific orientations like (104) and (1̅08) are beneficial for stable cycling and high lithium-ion transport.
• This study provides guidelines for designing high-performance NMC cathodes by controlling epitaxial growth and defect engineering.