Safety concerns on conventional lithium ion batteries are attracting a lot of attention from both academia and industry with the rapid growth of the electric automobile market. Replacing flammable organic liquid electrolytes with nonflammable inorganic solid electrolytes can potentially eliminate the fire hazards. On the other hand, low-cost electrochemical energy storage technologies beyond lithium chemistry are also highly desired for large-scale energy storage applications. All-solid-state Na ion batteries are one of the promising candidates for grid-level energy storage owing to their low cost and outstanding safety properties. The key enabler of this technology is solid electrolyte with sufficiently high ionic conductivity at room temperature and good electrochemical stability. This work presents a group of novel sodium superionic conductors to address the foregoing issues, which is a topic currently receiving extensive attention in the field of electrochemistry and energy storage. Through a rational design approach and using facile solid-state reactions, a series of novel Na3SbSe4-xSx compounds were obtained. Na3SbSe4 shows a room temperature conductivity of 0.85 mS/cm, which is among the highest values reported for chalcogenide sodium conductors to date. The trend in conductivities and diffusion activation energies of this series of compounds provides interesting structure-property relationships for the Na-ion conductors. An all-solid-state Na-ion battery cell with Na3SbSe4 as electrolyte was successfully assembled and cycled at room temperature, demonstrating the promise of this group of chalcogenide-based compounds as solid electrolytes and new opportunities in Na ion conductors and solid-state batteries.

Chalcogenide-based compounds as sodium superionic conductors

255th National Meeting (2018)

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