Fast Charge Transfer across the Li₇La₃Zr₂O₁₂ Solid Electrolyte/LiCoO₂ Cathode Interface Enabled by an...

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Batteries

Background:

• Lithium garnet Li$_{7}$La$_{3}$Zr$_{2}$O$_{12}$ (LLZO) is a promising solid electrolyte for solid-state batteries.
• High interfacial resistance at the LLZO/cathode interface hinders battery performance, primarily due to high-temperature sintering requirements.

Purpose of the Study:

• Investigate the LLZO solid electrolyte/LiCoO$_{2}$ (LCO) cathode interface in an all-thin-film model system.
• Identify degradation processes during high-temperature cosintering and test interface modification solutions.

Main Methods:

• Fabrication of an all-thin-film model system for LLZO/LCO interface investigation.
• Introduction of an in situ-lithiated Nb$_{2}$O$_{5}$ diffusion barrier at the interface.
• In situ and ex situ characterization of interface properties and degradation.

Main Results:

• Reduced LLZO/LCO charge transfer resistance to approximately 50 Ω cm$^{2}$, a threefold decrease.
• Achieved high discharge capacities (140 mA h g$^{-1}$ at 1C) and retained 60% capacity at 10C over 100 cycles.
• Demonstrated high charge-discharge rates due to low interfacial resistance and high LLZO conductivity.

Conclusions:

• The Nb$_{2}$O$_{5}$ diffusion barrier effectively lowers interfacial resistance in thin-film solid-state batteries.
• This approach enables investigation and development of high-power-density thin-film solid-state batteries.
• The study represents a significant advancement in solid-state battery technology.