Li-ion transport at the interface between a graphite anode and Li₂CO₃ solid electrolyte interphase: ab initio...

Area of Science:

• Battery electrochemistry
• Interface science
• Materials science

Background:

• Lithium-ion (Li+) transport across the anode and solid electrolyte interphase (SEI) is critical for battery performance.
• Understanding interfacial properties is key to controlling Li+ migration.

Purpose of the Study:

• Investigate Li+ migration between graphite anode (LiCx) and Li2CO3 SEI film.
• Analyze structural, electronic, and free energy properties of Li+ transport.
• Compare different graphite edge terminations and Li+ transfer scenarios.

Main Methods:

• Utilized ab initio molecular dynamics and free energy calculations.
• Validated computational models with bulk Li2CO3 and LiCx systems.
• Sampled interfacial structures under thermodynamic equilibrium.

Main Results:

• OH- and mixed-terminated graphite edges exhibited larger binding energies.
• Li+ intercalation barriers from SEI to LiC24 exceeded 1.2 eV across all cases.
• Calculated Li+ charges remained largely unchanged during intercalation.
• Modeled free energy profiles under charging/discharging, revealing a ca. 0.5 eV barrier during charging.

Conclusions:

• The study provides crucial insights into Li+ transport mechanisms at battery interfaces.
• The findings contribute to understanding and controlling Li+ migration for enhanced battery design.
• The developed model aligns with experimental observations for charging processes.