Mixed network former effect on the ion-dynamics of Sodium Alumino- Phospho-Silicate glasses

SR Keshri and I Mandal and A Gaddam and S Ganisetti and S Haque and C Venkateswaran and GE Stan and T Tite and A Ghosh and NN Gosvami and NMA Krishnan and AR Allu, ACTA MATERIALIA, 288, 120837 (2025).

DOI: 10.1016/j.actamat.2025.120837

Developing new glass electrolytes with the necessary room-temperature ionic conductivity (similar to 10(-3) Scm(-1)) for solid- state batteries, especially sodium-ion (Na+) batteries, has been impeded by the lack of a clear relationship between composition, structure, and conductivity in glass materials. This study highlights the impact of the mixed glass formers on the structure, Na+-ion dynamics, and glass conductivity. To this end, we substituted SiO2 for P2O5 in sodium alumino-phosphate glass while maintaining a constant molar concentration of Al2O3 and Na2O. A detailed analysis combining molecular simulations and experiments revealed that the glass containing 15 mol% SiO2 exhibited the highest DC ionic conductivity of similar to 9 x 10(-6) Scm(-1) at 473 K, followed by a decrease for 20 mol% SiO2. To understand this behavior, microscopic characteristic length such as critical hopping distance and Na+ diffusion coefficients were correlated with structural changes using AC conductivity analysis. Altogether, we elucidate the composition-dependent Na+ ion dynamics in the alumino- phosphate glass system, with factors like mobile charge carrier concentration, ion mobility, and coulombic forces influenced by the structure of different glass compositions.

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