posted on 2022-02-04, 22:43authored byIndrajeet Mandal, Saswata Chakraborty, K. Jayanthi, Manasi Ghosh, Krishna K. Dey, K. Annapurna, Jayanta Mukhopadhyay, Abhijit Das Sharma, Amarnath R. Allu
Achieving high ion conductivity in
glass-based Na-ion conducting
materials for their applications as solid electrolytes in batteries
is still challenging owing to the vague knowledge on the factors governing
Na-ion dynamics. In the present study, an attempt has been made to
identify the factors affecting the sodium-ion dynamics through structure
and conductivity property correlation for the 37.5Na2O–37.5P2O5–15Al2O3–10NaF
(FS-0; mol %) glass system with varied concentrations of Na2SO4. 31P, 27Al, and 23Na MAS NMR (magic-angle spinning nuclear magnetic resonance) and
Raman spectroscopy are employed to assess the structural modifications,
and impedance spectroscopy is used to measure the variations in ionic
conductivity on the addition of Na2SO4 in the
FS-0 glass. Raman spectra and MAS NMR analysis indicate that the quantity
of P–O–Na bonds and sulfate (SO42–) units surrounded by sodium increase with increasing Na2SO4 concentration. Impedance analysis reveals that the
conductivity of FS-0 glass enhances by 1 order with the addition of
6 mol % Na2SO4. We identify from the ac-conductivity
spectral analysis that the concentration of charge carriers and the
critical hopping length of mobile cations increase with the addition
of 6 mol % Na2SO4. Overall, we reveal that the
structural modifications, Na-ion concentration, and the shallower
potential well that is created for sodium due to its interaction with
the nearest neighboring cations affect the Na-ion dynamics. The information
obtained from the present study certainly helps to optimize the chemical
composition of glasses demonstrating high ionic conductivity.