Na3.4Zr2Si2.4P0.6O12 Electrolyte for Sodium Solid-State Batteries

• Grant number: 25/22474-1
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: December 01, 2025
• End date: November 30, 2026
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Lilian Menezes de Jesus
• Grantee: Lissa David Guidolin
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

Solid-state batteries are promising candidates for next-generation energy storage, combining high energy density, enhanced safety, and fast-charging capability. One of the main challenges lies in developing solid electrolytes with ionic conductivities comparable to those of liquids (~1-10 mS¿cm¿¹), while also addressing cost and sustainability. In this context, sodium batteries emerge as a viable alternative to lithium-based ones, as they rely on an abundant element. Among solid electrolytes, Na¿Zr¿Si¿PO¿¿ (with NaSICON structure) stands out due to its high ionic conductivity at room temperature (~0.7 mS¿cm¿¹), thermal stability, and compatibility with metallic sodium. Building on this material, recent studies have shown a strong dependence of ionic conductivity on the Si/P ratio in Na¿¿¿Zr¿Si¿¿¿P¿¿¿O¿¿ (0 ¿ x ¿ 0.6), ranging from 0.65 to 5.09 mS¿cm¿¹, with a maximum at x = 0.4 (Si/P = 2.4/0.6). However, the structural and microstructural mechanisms responsible for this enhancement are not yet fully understood. This project proposes the synthesis of the Na¿.¿Zr¿Si¿.¿P¿.¿O¿¿ composition and its sintering via flash sintering, an electric-field-assisted technique that enables ultrafast densification at reduced temperatures, minimizing Na and P losses and the formation of secondary phases. The goal is to obtain dense ceramics with total ionic conductivity above 5 mS¿cm¿¹, combining energy efficiency and short processing time. Samples will be characterized by X-ray diffraction, scanning electron microscopy, and impedance spectroscopy, aiming to advance the development of sustainable, high-performance solid-state sodium batteries.