Microwave-Driven Densification of NASICON-type LATP: A Fast Route Toward Efficient Solid-State Electrolytes

The transition from flammable liquid electrolytes to safer solid-state electrolytes is essential for next-generation batteries. Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 (LATP) is a promising NASICON-type electrolyte, but its application is hindered by energy-intensive high-temperature sintering. This work demonstrates microwave sintering as a rapid and efficient route to fabricate dense, highly conductive LATP. Green bodies with a relative density of 71% were obtained by combined uniaxial and isostatic pressing, followed by microwave sintering between 800 and 1100 ºC for only 10 minutes. Optimal densification (91.4%) was achieved at 1000 ºC, while higher temperatures led to abnormal grain growth and rutile-TiO 2 formation. Electrochemical impedance spectroscopy revealed a strong reduction in grain-boundary resistance above 950 ºC. LATP sintered at 1000 ºC exhibited an ionic conductivity of 5·10 -4 S cm -1 and an activation energy of 0.20 eV. Symmetric Li|LATP|Li cells showed stable cycling over 500 h with low overpotentials, confirming excellent transport and mechanical integrity.