Simultaneously Improved Cubic Phase Stability and Li-Ion Conductivity in Garnet-Type Solid Electrolytes Enabled by...

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Garnet-type solid electrolytes (SEs) are crucial for next-generation batteries.
• Enhancing both phase stability and ionic conductivity in SEs remains a challenge.
• Lithium-ion conductivity is vital for battery performance.

Purpose of the Study:

• To simultaneously improve the cubic phase stability and Li-ion conductivity of garnet-type SEs.
• To investigate the effect of excess Li/Al on the microstructure and properties of garnet SEs.
• To provide insights for practical applications of garnet SEs in all-solid-state batteries.

Main Methods:

• Synthesizing garnet-type solid electrolytes with excess Li/Al.
• Characterizing microstructure, including grain size and Al occupation sites.
• Measuring Li-ion conductivity and phase stability under applied voltage.
• Analyzing phase transformations using advanced techniques.

Main Results:

• Excess Li/Al addition led to significantly larger grain sizes (up to 170 μm).
• Preferential Al occupation at 96h sites was observed, contrary to previous findings.
• Simultaneous enhancement of cubic phase stability and Li-ion conductivity was achieved.
• The material maintained high ionic conductivity under battery operating conditions.

Conclusions:

• Excess Li/Al is an effective strategy for simultaneously improving cubic phase stability and Li-ion conductivity in garnet SEs.
• The observed preferential Al occupation plays a key role in stabilizing the cubic phase.
• These findings offer a promising pathway for developing advanced garnet-based solid-state batteries without post-treatments.