Ionic Conductivity of Na3Al2P3O12 Glass Electrolytes Role of Charge Compensators
authors Keshri, SR; Ganisetti, S; Kumar, R; Gaddam, A; Illath, K; Ajithkumar, TG; Balaji, S; Annapurna, K; Nasani, N; Krishnan, NMA; Allu, AR
nationality International
journal INORGANIC CHEMISTRY
keywords SODIUM-PHOSPHATE GLASSES; MEDIUM-RANGE ORDER; OXIDE GLASSES; ALKALI OXIDE; THERMODYNAMIC APPROACH; ALPO4-SIO2 GLASSES; NMR INVESTIGATIONS; NA-23 MAS; SI-29; RAMAN
abstract In glasses, a sodium ion (Na+) is a significant mobile cation that takes up a dual role, that is, as a charge compensator and also as a network modifier. As a network modifier, Na+ cations modify the structural distributions and create nonbridging oxygens. As a charge compensator, Na+ cations provide imbalanced charge for oxygen that is linked between two network-forming tetrahedra. However, the factors controlling the mobility of Na+ ions in glasses, which in turn affects the ionic conductivity, remain unclear. In the current work, using high-fidelity experiments and atomistic simulations, we demonstrate that the ionic conductivity of the Na3Al2P3O12 (Si0) glass material is dependent not only on the concentration of Na+ charge carriers but also on the number of charge-compensated oxygens within its first coordination sphere. To investigate, we chose a series of glasses formulated by the substitution of Si for P in Si0 glass based on the hypothesis that Si substitution in the presence of Na+ cations increases the number of SiOAl bonds, which enhances the role of Na as a charge compensator. The structural and conductivity properties of bulk glass materials are evaluated by molecular dynamics (MD) simulations, magic angle spinning-nuclear magnetic resonance, Raman spectroscopy, and impedance spectroscopy. We observe that the increasing number of charge-imbalanced bridging oxygens (BOs) with the substitution of Si for P in Si0 glass enhances the ionic conductivity by an order of magnitudefrom 3.7 x 10(-8) S.cm(-1) to 3.3 x 10(7) S.cm(-1) at 100 degrees C. By rigorously quantifying the channel regions in the glass structure, using MD simulations, we demonstrate that the enhanced ionic conductivity can be attributed to the increased connectivity of Na-rich channels because of the increased charge-compensated BOs around the Na atoms. Overall, this study provides new insights for designing next-generation glass-based electrolytes with superior ionic conductivity for Na-ion batteries
publisher AMER CHEMICAL SOC
issn 0020-1669
isbn 1520-510X
year published 2021
volume 60
issue 17
beginning page 12893
ending page 12905
digital object identifier (doi) 10.1021/acs.inorgchem.1c01280
web of science category 13
subject category Chemistry, Inorganic & Nuclear
unique article identifier WOS:000695585400035
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journal impact factor 4.825
5 year journal impact factor 4.501
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