Decoupled Ion Transport in Protein-Based Solid Electrolyte through Ab Initio Calculations and Experiments.

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Developing advanced solid polymer electrolytes requires decoupling ion motion from segmental relaxation for high ionic conductivity and mechanical strength.
• Previous research introduced decoupled ion transport in a novel protein-based solid electrolyte.
• Understanding ion interaction and transport mechanisms is crucial for optimizing electrolyte performance.

Purpose of the Study:

• To investigate the detailed ion interaction and transport mechanisms in protein-based solid electrolytes.
• To elucidate the role of charged amino acids in facilitating ion transport.
• To provide a fundamental understanding supporting experimental findings.

Main Methods:

• First-principles density functional theory (DFT) calculations in a vacuum.
• Analysis of ion interactions, specifically focusing on charged amino acids (Arginine and Lysine) and anions (perchlorate).
• Experimental validation using two protein solid electrolytes (soy protein and zein).

Main Results:

• Charged amino acids (Arginine, Lysine) effectively anchor perchlorate anions.
• Anchored anions create additional hopping sites, facilitating lithium-ion (Li+) transport.
• Soy protein electrolyte, rich in charged amino acids, exhibited significantly higher ionic conductivity and lower activation energy than zein electrolyte.

Conclusions:

• Charged amino acids play a critical role in enhancing ionic conductivity in protein-based solid electrolytes.
• The mechanism involves specific anion anchoring by charged residues, which promotes Li+ transport.
• These findings offer a pathway for designing high-performance solid polymer electrolytes by leveraging amino acid functionalities.