Electrochemical Li⁺ Insertion/Extraction Reactions at LiPON/Epitaxial Graphene Interfaces

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Graphene's electrochemical properties are crucial for energy storage applications.
• Understanding Li+ intercalation in few-layer graphene is key to developing advanced batteries.
• Existing methods struggle with precise electrochemical analysis of controlled graphene layers.

Purpose of the Study:

• To investigate Li+ insertion/extraction redox reactions in 1-2 interlayers of graphene (Gr) on SiC substrates.
• To evaluate the performance of lithium phosphorus oxynitride glass (LiPON) as a solid-state electrolyte for Gr electrodes.
• To establish a reliable method for electrochemical measurements of few-layer graphene.

Main Methods:

• Electrochemical investigation of Li+ redox reactions using LiPON solid-state electrolyte on epitaxial graphene.
• Cyclic voltammetry to analyze reduction/oxidation peaks and surface capacity.
• Charge transfer resistance measurements during Li+ insertion/extraction.

Main Results:

• Graphene electrodes with <2 layers showed distinct single reduction and 1-2 oxidation peaks below +0.21 V.
• LiPON electrolyte prevented solid electrolyte interphase formation and Li+ desolvation.
• Li+ insertion/extraction exhibited different charge transfer resistances at the single interlayer level.
• Measurements with liquid electrolytes on transferred graphene were unreliable.

Conclusions:

• The proposed method using epitaxial graphene and LiPON is effective for precise electrochemical measurements of few-layer graphene.
• This technique allows for the study of Li+ behavior at the single interlayer level.
• The findings contribute to the development of high-performance graphene-based energy storage devices.