Effect of solid-electrolyte pellet density on failure of solid-state batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Solid-state batteries (SSBs) offer higher energy density and safety than Li-ion batteries.
• Lithium dendrite penetration and short circuits are critical failure modes in SSBs.

Purpose of the Study:

• To investigate the relationship between solid electrolyte density and lithium filament growth.
• To identify critical density thresholds for preventing dendrite formation in SSBs.

Main Methods:

• Quantification of microstructural properties (porosity, pore connectivity, tortuosity) using focused ion beam-scanning electron microscopy tomography.
• Permeability tests to assess electrolyte properties.
• Modeling of lithium filament growth within pores of varying sizes (0.2–2 μm).

Main Results:

• Lithium filament growth is suppressed in solid-electrolyte pellets with relative densities exceeding approximately 95%.
• Below the 95% density threshold, increasing density accelerates lithium filament growth and short-circuiting due to percolating pores.
• Microstructural analysis revealed key properties influencing dendrite propagation.

Conclusions:

• Solid electrolyte density is a critical parameter for preventing lithium dendrite formation in SSBs.
• Achieving a relative density above 95% is crucial for designing safer, dendrite-free solid-state batteries.
• Understanding pore structure and its relation to density provides guidelines for SSB design and failure mitigation.