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Lithium ion conduction in lithium metaphosphate based systems
Date Issued
01-09-2007
Author(s)
Money, B. K.
Hariharan, K.
Abstract
A comparative investigation on Li+ ion transport has been carried out in various phases of lithium metaphosphate such as (i) crystalline LiPO3, (ii) glassy form as mol∈% 50Li2O-50P 2O5, synthesized by melt-quenching process, (iii) single phase glass-ceramic LiPO3 obtained through controlled heat treatment of mol∈% 50Li2O-50P2O5 and (iv) newly identified polymer-metal salt complex (PEO)6: LiPO3. All of the above materials have been characterized through XRD, DSC, optical microscopy and impedance spectroscopy techniques. The Li+ ions, migrating with an activation energy value of 1.4 eV through "interstitial mechanism" in polycrystalline LiPO3, exhibited a dc conductivity value of 2.5×10-8 Scm-1 at 280 °C. The above conductivity value was enhanced by four orders of magnitude in Li 2O-P2O5 glass, with an activation energy value of 0.72 eV. The glass subjected to controlled heat treatment devitrified into single phase glass-ceramic, as revealed by XRD and optical microscopy studies. The glass-ceramic exhibited better conduction characteristics compared to polycrystalline LiPO3. Polycrystalline LiPO3, complexed with polymer PEO has exhibited a conductivity value of 3.1×10-7 Scm-1 at 78 °C with activation energies of 0.21 and 0.88 eV for Li+ ion migration above and below the softening point of the polymer, respectively. © Springer-Verlag 2007.
Volume
88