First-Principles Study on the Interfacial Cathode-Contact Stability and Li Diffusivity of N-Doped Li₆Zr₂O₇ for...

Area of Science:

• Materials Science
• Electrochemistry
• Computational Materials Science

Background:

• All-solid-state lithium-ion batteries (ASSBs) require stable and conductive materials for electrolytes and interfaces.
• Lithium Zirconate (Li$_{6}$Zr$_{2}$O$_{7}$) is explored for its potential as a lithium ionic conductor.
• Optimizing interfaces between cathode materials and solid electrolytes is crucial for ASSB performance.

Purpose of the Study:

• To investigate the electrochemical stability and Li-ion transport properties of Nitrogen-doped Lithium Zirconate (LZON).
• To evaluate LZON as a dual-use material for cathode-coating layers (CCL) and solid electrolytes (SE) in ASSBs.
• To analyze the interface between LZON and Lithium Cobalt Oxide (LiCoO$_{2}$) cathode.

Main Methods:

• First-principles density functional theory (DFT) calculations.
• Thermodynamic free energy calculations for chemical stability.
• Explicit hetero-interface modeling and climbing-image nudged elastic band calculations for Li-ion migration.
• Ab-initio and machine-learning-based molecular dynamics simulations.

Main Results:

• LZON exhibits chemical stability against common cathode materials.
• The LCO(104)|LZON(001) interface demonstrates strong adhesion, low strain, and facilitates stable cell charging.
• N-doping significantly enhances Li-ion diffusivity in bulk LZON.
• N dopants prefer the LZON bulk, maintaining favorable interface electronic structure for stable charging.

Conclusions:

• Nitrogen-doped Li$_{6}$Zr$_{2}$O$_{7}$ is a promising material for both cathode coatings and solid electrolytes in ASSBs.
• The material offers excellent electrochemical stability and enhanced ionic conductivity.
• The findings support the development of advanced ASSBs with improved safety and performance.