Enabling High-Performance Hybrid Solid-State Batteries by Improving the Microstructure of Free-Standing LATP/LFP...

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Phosphate lithium-ion conductors like Li_1.5Al_0.5Ti_1.5(PO₄)₃ (LATP) are promising for solid-state batteries.
• High sintering temperatures for LATP-based components lead to surface roughness, hindering cell integration and energy density.
• Developing scalable fabrication methods for high-performance solid-state battery cathodes is crucial.

Purpose of the Study:

• To develop efficient, free-standing ceramic cathodes using LATP and LiFePO₄ (LFP).
• To overcome challenges associated with high sintering temperatures in LATP-based materials.
• To improve the integration of composite cathodes in solid-state batteries for enhanced energy density.

Main Methods:

• Utilizing a scalable tape casting process for cathode fabrication.
• Incorporating 5 wt% Li₂WO₄ (LWO) into the LATP/LFP casting slurry.
• Optimizing the fabrication process to control sintering temperature and microstructure.

Main Results:

• Achieved mechanically stable, electronically conductive, and free-standing LATP/LFP cathodes.
• LWO addition lowered sintering temperature without altering phase composition.
• Resulting cathodes exhibited smooth, homogeneous surfaces, enabling thin polymer separator deposition.
• Fabricated solid-state cells demonstrated high volumetric (289 Wh dm^-3) and gravimetric (180 Wh kg^-1) energy densities.
• Cells achieved >99% Coulombic efficiency after 30 cycles at 30 °C.

Conclusions:

• The addition of LWO and optimized tape casting is an effective strategy for producing high-quality LATP/LFP composite cathodes.
• This method addresses the high sintering temperature challenge, enabling robust cell fabrication.
• The developed cathodes contribute to achieving high energy density and stable cycling performance in solid-state batteries.