Heteroionic Interfaces in Hybrid Solid-State Batteries─Current Constriction at the Interface between Different Solid...

Area of Science:

• Materials Science
• Electrochemistry
• Computational Modeling

Background:

• Solid-state batteries offer advantages over liquid electrolyte systems.
• Hybrid cell concepts utilizing diverse solid electrolytes are promising but face challenges at interfaces.
• Charge transfer kinetics and physical contact at heteroionic interfaces critically affect performance.

Purpose of the Study:

• To investigate how interface morphology influences the impedance response in solid electrolyte bilayers.
• To differentiate between geometric interface effects and intrinsic material properties in impedance spectra.
• To provide insights for accurate electrochemical characterization of solid electrolyte interfaces.

Main Methods:

• Microstructure-resolved electric network computations were employed.
• Analysis focused on homogeneous bilayer systems with varying interface properties.
• An experimental oxide-sulfide multilayer case study was used for validation.

Main Results:

• Porous interfaces create geometric impedance signatures mimicking charge transfer processes.
• Current constriction at interfaces significantly affects impedance response.
• Interface resistance and capacitance are sensitive to contact area, distribution, pore capacitance, and local conductivity.

Conclusions:

• Geometric effects at interfaces can be misinterpreted as electrochemical processes, complicating impedance analysis.
• Accurate assessment of solid electrolyte material parameters requires careful consideration of interface morphology.
• The findings are broadly applicable to heterojunctions in various electrochemical systems.