Solid electrolyte interphase formation by propylene carbonate reduction for lithium anode.

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Naturally formed solid electrolyte interphase (SEI) on lithium (Li) metal anodes is fragile, leading to poor cycling stability in batteries.
• Artificial SEI layers are crucial for enhancing the stability and performance of Li metal anodes.
• Using non-Li metal substrates for Li metal electrodes offers a more practical approach than direct Li metal anodes.

Purpose of the Study:

• To investigate the electrochemical reduction of propylene carbonate (PC) as a method for forming an artificial SEI layer on Li metal anodes.
• To understand the reaction mechanisms and product formation during PC reduction.
• To optimize SEI formation for improved Li plating/stripping efficiency.

Main Methods:

• Electrochemical evaluation of propylene carbonate (PC) reduction on Li metal.
• Cyclic voltammetry and controlled potential electrolysis to study reduction stages.
• Analysis of SEI film composition and morphology.

Main Results:

• PC reduction occurs in two distinct potential regions.
• Higher potentials (>0.85 V vs. Li/Li⁺) yield soluble, re-oxidizable radical anions.
• Lower potentials (0.85–0.55 V vs. Li/Li⁺) form insoluble Li₂CO₃ and organic lithium salts, constructing the SEI film.
• Controlled reduction rates improve SEI morphology and Li plating/stripping cycling efficiency.

Conclusions:

• Electrochemical reduction of PC is a viable strategy for creating high-quality artificial SEI layers.
• Controlling the PC reduction process enables optimization of SEI properties.
• This approach offers a fundamental concept for enhancing the stability and performance of lithium metal batteries.