Theoretical analysis of electrode-dependent interfacial structures on hydrate-melt electrolytes

Area of Science:

• Electrochemistry
• Materials Science
• Computational Chemistry

Background:

• Aqueous electrolytes present a safer alternative to conventional lithium-ion batteries for large-scale applications like stationary energy storage.
• Current research focuses on overcoming the limitations of aqueous electrolytes, particularly their stability and performance with various electrode materials.

Purpose of the Study:

• To investigate the interfacial mechanisms governing the reductive stability of a novel hydrate-melt electrolyte, Li(TFSI)_0.7(BETI)_0.3·2H₂O.
• To understand how electrode material and potential influence the electrolyte's stability and interfacial structure.

Main Methods:

• Utilized molecular dynamics simulations to analyze interfacial structures on carbon (C), aluminum (Al), and platinum (Pt) electrodes.
• Simulations were conducted under constrained electrode potentials to mimic battery operating conditions.

Main Results:

• High adsorption forces on metal electrodes increase local water density, consequently reducing the electrolyte's reductive stability.
• On platinum (Pt) at low potentials, unfavorable anion orientation hinders stable solid electrolyte interphase formation, leading to hydrogen evolution.
• Electrode material and potential are critical factors determining interfacial structure and electrolyte stability.

Conclusions:

• The interfacial structure, dictated by electrode material and applied potential, is the primary determinant of hydrate-melt electrolyte reductive stability.
• Understanding these interfacial phenomena is crucial for designing stable and safe aqueous electrolytes for next-generation batteries.