Investigation of Charge Transfer Kinetics in Multilayer PEO/LLZO Solid-State Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Solid electrolytes in lithium-metal batteries promise higher energy and power densities than current lithium-ion technologies.
• Challenges include poor interfacial contact in ceramic electrolytes and insufficient ionic conductivity in polymer electrolytes.
• Composite solid electrolytes aim to combine the benefits of both ceramic and polymer electrolytes for improved performance.

Purpose of the Study:

• To systematically investigate the charge transfer kinetics at interfaces within composite solid electrolytes.
• To understand the factors limiting ion transport and their impact on overall electrolyte performance.
• To provide insights for the rational design of next-generation solid-state batteries.

Main Methods:

• Utilized multilayer lithium lanthanum zirconium oxide (LLZO)/poly(ethylene oxide) (PEO) architectures as model composite solid electrolytes.
• Employed electrochemical impedance spectroscopy and DC polarization measurements to analyze interfacial properties.
• Applied a Butler-Volmer model incorporating film resistance to describe charge transfer kinetics.

Main Results:

• Observed nonlinear charge transfer kinetics at lithium/PEO and PEO/LLZO interfaces.
• Identified ion transfer limitations, described by a Butler-Volmer model with film resistance, as rate-limiting steps.
• Determined that solid electrolyte interphase and contamination layers significantly contribute to interfacial impedance.

Conclusions:

• Charge transfer kinetics in composite solid electrolytes are complex and interface-dependent.
• Interfacial ion transport and contamination layers are critical factors affecting impedance.
• High-temperature treatment of LLZO can mitigate interfacial contamination, improving battery performance.