Exploring lithium ion interactions in graphite electrodes through non-equilibrium molecular dynamics and density...

Area of Science:

• Materials Science
• Computational Chemistry
• Electrochemistry

Background:

• Accurate simulation of lithium ion dynamics in graphite is essential for advanced battery development.
• Potential function selection critically impacts the fidelity of molecular dynamics (MD) simulations for intercalation and diffusion processes.

Purpose of the Study:

• To evaluate the suitability of different potential functions for simulating lithium ion behavior in graphite.
• To provide insights into lithium ion intercalation and diffusion kinetics within graphite electrodes.
• To establish a theoretical basis for optimizing lithium-ion battery performance.

Main Methods:

• Employed a hybrid approach combining non-equilibrium molecular dynamics (NEMD) and density-functional theory (DFT).
• Evaluated the AIREBO potential function for ordered lithium ion motion between graphite layers.
• Assessed the Tersoff potential function for folded lithium ion structures within graphite layers.

Main Results:

• AIREBO potential accurately models ordered lithium ion movement, aligning with Rüdorff-Hofmann (R-H) and Daumas-Hérold (D-H) models.
• Tersoff potential is suitable for localized lithium ion structures, consistent with the localized-domains model.
• Increasing lithium ion concentration decreases voltage, Young's modulus, and tensile strength in LiC₆.
• Lithium ion diffusion coefficients in graphite range widely from 10^-6 to 10^-16 cm² s^-1.

Conclusions:

• The choice of potential function (AIREBO vs. Tersoff) depends on the specific lithium ion arrangement within the graphite structure.
• Simulation results offer a theoretical framework for understanding lithium ion intercalation and diffusion mechanisms.
• Findings can guide the design and optimization of high-performance lithium-ion batteries.