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A Simple Method for the Study of Heteroionic Interface Impedances in Solid Electrolyte Multilayer Cells Containing
Sascha Kremer1,2, René Rekers1,2, Ujjawal Sigar1,2
1Institute of Physical Chemistry, Justus-Liebig-University Giessen, Heinrich-Buff-Ring 17, Giessen D-35392, Germany.
ACS Applied Materials & Interfaces
|August 9, 2024
Summary
Researchers developed a simple method to precisely measure interface resistance in hybrid solid-state batteries. This technique uses lithium lanthanum zirconium oxide (LLZO) with a lithium metal electrode to accurately evaluate heteroionic interface impedance, crucial for battery performance.
Area of Science:
- Materials Science
- Electrochemistry
- Solid-State Batteries
Background:
- Hybrid battery cells combining garnet-type lithium lanthanum zirconium oxide (LLZO) solid electrolytes with other electrolyte types are under investigation.
- Low-resistive heteroionic interfaces are critical in layered electrolytes to prevent operational overpotentials.
- Electrochemical impedance spectroscopy (EIS) is commonly used but often struggles to isolate interface impedance due to overlapping contributions.
Purpose of the Study:
- To develop a simplified and reliable method for accurately evaluating heteroionic interface impedance in LLZO-based hybrid battery cells.
- To overcome the limitations of traditional EIS methods that require complex four-point cells.
Main Methods:
- Utilized the reversible Li|LLZO interface, which exhibits fast charge transfer kinetics, to minimize electrode polarization effects.
- Employed symmetric two-point cells of the type Li|LLZO|electrolyte|LLZO|Li, leveraging the 'resistance-free' nature of the Li|LLZO interface.
- Tested the method on multilayer cells with tantalum-doped LLZO and a poly(ethylene oxide) (PEO)-based polymer electrolyte.
Main Results:
- Demonstrated that the Li|LLZO interface allows for precise evaluation of heteroionic interface impedance with negligible electrode contribution.
- Successfully applied the method to LLZO/PEO multilayer cells, obtaining reliable impedance data.
- Validated the results by comparing them with data from traditional four-point cells and two-point cells with ion-blocking electrodes.
Conclusions:
- The proposed two-point cell configuration with a reversible Li|LLZO interface offers a simple and accurate approach to study heteroionic interface impedances.
- This method significantly simplifies the characterization of interfaces in complex multilayer solid-state battery architectures.
- The findings are crucial for optimizing the design and performance of next-generation hybrid solid-state batteries.
