Flexible, Biocompatible Supercapacitors Weaved From Layered Phyllosilicates and Zwitterions via Ionicity

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Phyllosilicates like bentonite clay are abundant but limited in energy storage due to brittleness and poor conductivity.
• Conventional methods often require harmful solvents and synthetic binders for functional membranes.

Purpose of the Study:

• To develop a polymer-free, aqueous-based method for creating mechanically robust and ion-conductive clay membranes.
• To utilize betaine, a natural zwitterion, for intercalating into bentonite clay galleries.
• To introduce redox-active transition-metal ions for enhanced pseudocapacitive charge storage.

Main Methods:

• Ionic intercalation of betaine into bentonite clay galleries.
• Incorporation of transition-metal ions (Fe³⁺, Mn²⁺).
• Molecular dynamics simulations, rheo-impedance, and electrochemical impedance spectroscopy for characterization.

Main Results:

• Formation of free-standing, mechanically robust, and ion-conductive membranes.
• Development of all-clay supercapacitors functioning as electrodes and separators.
• Achieved energy density of 158 mWh/cm³ and power density of 5688 mW/cm³.
• Demonstrated biocompatibility and sustained performance over 30,000 cycles with ~75% capacitance retention.

Conclusions:

• Zwitterion-clay intercalation offers a simple, scalable, and sustainable route to biocompatible supercapacitors.
• The developed membranes are suitable for low-power applications demanding mechanical flexibility and material sustainability.
• This approach overcomes limitations of traditional clay-based energy storage materials.