Aqueous electrolyte-mediated reversible K⁺ ion insertion into graphite

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Potassium-ion batteries (KIBs) are a promising alternative to lithium-ion batteries due to the abundance of potassium.
• Graphite is a common anode material in rechargeable batteries, but its performance in KIBs is limited by K+ ion diffusion kinetics.

Purpose of the Study:

• To investigate the feasibility of reversible potassium-ion insertion into graphite in an aqueous electrolyte.
• To compare the potassium-ion diffusion characteristics in natural graphite versus pyrolytic graphite.

Main Methods:

• Electrochemical cycling of natural and pyrolytic graphite electrodes in a potassium-ion containing aqueous electrolyte.
• Analysis of ion diffusion kinetics using electrochemical techniques.

Main Results:

• Demonstrated reversible K+ ion insertion and extraction in graphite electrodes within an aqueous system.
• Observed significantly more facile K+ ion diffusion in natural graphite compared to pyrolytic graphite.
• Identified factors influencing K+ ion diffusion rates in different graphite structures.

Conclusions:

• Aqueous electrolytes are viable for reversible potassium-ion intercalation into graphite.
• Natural graphite exhibits superior potassium-ion transport properties over pyrolytic graphite for potential battery applications.
• Further research into graphite modification could enhance KIB performance.