Effect of current density on the solid electrolyte interphase formation at the lithium∣Li₆PS₅Cl interface

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Developing reliable all-solid-state lithium batteries requires understanding the solid electrolyte interphase (SEI) at the lithium metal electrode interface.
• The chemical composition and morphology of the SEI significantly impact battery performance and longevity.

Purpose of the Study:

• To investigate the influence of lithium plating current density on SEI formation.
• To elucidate the chemical and morphological evolution of the SEI on Li6PS5Cl solid-state electrolytes.
• To correlate SEI properties with interfacial resistance.

Main Methods:

• X-ray photoemission spectroscopy (XPS) was used to analyze SEI composition during in-situ lithium plating.
• Electron beam was utilized for lithium plating on Li6PS5Cl pellets.
• Electrochemical impedance spectroscopy (EIS) validated XPS findings in full cells.

Main Results:

• XPS analysis revealed that lithium plating current density dictates SEI evolution.
• Optimized current density promotes a uniform and Li3P-rich SEI.
• The Li3P-rich SEI effectively decreases the electrode-solid electrolyte interfacial resistance.

Conclusions:

• Lithium plating current density is a critical parameter for controlling SEI properties.
• A uniform, ionically conductive SEI is achievable, leading to reduced interfacial resistance.
• These findings are vital for advancing the performance of solid-state lithium batteries.