Achieving Fast and Efficient K⁺ Intercalation on Ultrathin Graphene Electrodes Modified by a Li⁺ Based...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Advancing beyond lithium-ion (Li+) batteries necessitates exploring alternative ion intercalation chemistries, such as potassium-ion (K+) systems.
• Developing high-performance K+ intercalation electrodes is crucial for next-generation battery technologies.
• Few-layer graphene (FLG) serves as a model system for investigating fundamental ion intercalation mechanisms.

Purpose of the Study:

• To demonstrate a method for significantly enhancing K+ intercalation performance in FLG electrodes.
• To investigate the role of the solid-electrolyte interphase (SEI) in K+ intercalation.
• To establish FLG as a platform for fundamental studies of ion intercalation.

Main Methods:

• Conditioning ultrathin few-layer graphene (FLG) electrodes with a Li+ containing electrolyte to form a Li+-based SEI.
• Electrochemical characterization including cyclic voltammetry (CV) and galvanostatic cycling.
• In situ Raman spectroscopy to confirm ion intercalation processes.
• Mass spectrometric depth profiling to verify K+ transport.

Main Results:

• A Li+-based SEI on FLG electrodes enabled efficient K+ intercalation, unlike K+-based electrolytes which caused plating.
• Discrete staging-type phase transitions were observed via CV up to 100 mVs-1.
• In situ Raman spectroscopy confirmed K+ intercalation processes.
• The modified interface achieved fast charge-discharge rates (up to ~360C) and excellent cycling stability (1000 cycles at 10C).
• Mass spectrometry confirmed that the SEI promoted K+ transport.

Conclusions:

• Conditioning the SEI with a Li+-containing electrolyte is a viable strategy to improve K+ intercalation electrode performance.
• FLG electrodes with a Li+-conditioned SEI offer a promising avenue for practical K-ion batteries.
• FLG serves as an effective model system for fundamental research into ion intercalation mechanisms and SEI effects.