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Reducing Impedance at a Li-Metal Anode/Garnet-Type Electrolyte Interface Implementing Chemically Resolvable In Layers
Marius Müller1, Johannes Schmieg1,2, Sebastian Dierickx1
1Institute for Applied Materials (IAM-ET), Karlsruhe Institute of Technology (KIT), D-76131 Karlsruhe, Germany.
ACS Applied Materials & Interfaces
|March 17, 2022
Summary
Magnetron-sputtered indium enhances lithium metal anode contact with garnet-type Li7La3Zr2O12 solid electrolytes. Optimized indium layers improve interface resistance and cycling stability for all-solid-state batteries.
Area of Science:
- Materials Science
- Electrochemistry
- Solid-state battery technology
Background:
- Garnet-type Li7La3Zr2O12 (LLZO) is a promising solid electrolyte for all-solid-state lithium-ion batteries due to its chemical stability.
- Achieving uniform lithium metal wetting and high surface coverage on LLZO remains a significant challenge for practical applications.
Purpose of the Study:
- To investigate the efficacy of magnetron-sputtered indium as an interfacial modification layer between lithium metal anodes and LLZO solid electrolytes.
- To evaluate the impact of indium layer preparation parameters on interface properties, including surface coverage, resistance, and electrochemical performance.
Main Methods:
- Fabrication of Li(In)/LLZO/Li(In) symmetrical model cells using magnetron sputtering.
- Optimization of indium layer thickness and annealing conditions (temperature, time).
- Characterization using Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDXS), and X-ray microtomography.
- Electrochemical testing including impedance spectroscopy, cycling stability, and critical current density measurements.
Main Results:
- Annealing of indium layers led to their complete dissolution into the lithium anode.
- A 300 nm indium layer annealed at 220 °C for 10 hours achieved >80% surface coverage, yielding an interface resistance (Rint) of 12.4 Ω·cm2.
- The critical current density was determined to be 200-500 μA/cm2, with higher values negatively impacting cell stability.
- Post-voltage breakdown analysis revealed lithium dendrite growth along grain boundaries in LLZO, indicating short-circuiting.
Conclusions:
- Magnetron-sputtered indium is a viable interfacial modification for improving lithium metal contact with LLZO electrolytes.
- Optimized indium layers significantly reduce interface resistance and enhance reproducibility.
- Grain boundary characteristics in LLZO are crucial for lithium deposition behavior and overall solid electrolyte failure mechanisms.
