Heavily Tungsten-Doped Sodium Thioantimonate Solid-State Electrolytes with Exceptionally Low Activation Energy for...

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Solid-state electrolytes (SSEs) are crucial for developing safer and more efficient batteries.
• Reducing cation diffusion activation energy is key to enhancing ionic conductivity in SSEs.
• Tungsten (W) doping in sodium thioantimonates is explored for improved performance.

Purpose of the Study:

• To develop novel tungsten-doped sodium thioantimonate solid-state electrolytes (SSEs).
• To investigate the effect of high tungsten content on the structure and ionic conductivity of SSEs.
• To evaluate the performance of these SSEs in all-solid-state sodium batteries.

Main Methods:

• Synthesis of heavily W-doped sodium thioantimonate SSEs (Na2.895 W0.3 Sb0.7 S4 and Na2.7 W0.3 Sb0.7 S4).
• Characterization of structural properties and ionic conductivity at various temperatures.
• Computational analysis of diffusion mechanisms.
• Fabrication and testing of an all-solid-state battery (ASSB) prototype.

Main Results:

• Achieved exceptionally low activation energies (0.09 eV and 0.12 eV) and enhanced room temperature ionic conductivity (24.2 mS/cm and 14.5 mS/cm).
• Demonstrated a total ionic conductivity of 5.5 mS/cm at -15°C for Na2.895 W0.3 Sb0.7 S4.
• Observed novel pseudo-cubic or orthorhombic structures due to 30% W doping.
• Identified multiple diffusion mechanisms contributing to high conductivity.
• An ASSB prototype achieved a reversible capacity of 400 mAh/g.

Conclusions:

• High tungsten doping effectively reduces activation energy and enhances ionic conductivity in sodium thioantimonate SSEs.
• The novel SSEs facilitate efficient ion transport through combined diffusion mechanisms.
• These W-doped SSEs show great promise for high-performance, low-temperature all-solid-state sodium batteries.