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Lecture

Electromotive force and calorimetric study of Li-Pb-Sb alloys

Thursday (27.09.2018)
11:30 - 11:45 S1/01 - A01
Part of:


Liquid metal battery (LMB) developed by group of prof. Sadoway [1] at MIT has liquid Pb-Sb alloy positive electrode, liquid salt electrolyte, and liquid lithium negative electrode, self segregated into distinct layers. Upon discharge of the battery the liquid Pb-Sb electrode is lithiated and Li-Pb-Sb ternary alloy is formed. The phase diagram of Li-Pb-Sb system is unknown, and this system has not yet been thermodynamically studied. We applied drop calorimetry and electromotive force measurements to study Li-Pb-Sb alloys.


Partial and integral enthalpies of mixing of ternary Li-Pb-Sb alloys were measured at 923 and 1023 K with drop calorimetry. In total 12 sections were studied of fixed molar ratios of Li to Pb equal to 1/9, 1/3, 2/3, 1, 3/2, Pb to Sb equal to 3/1, 1 , 1/3 and Li to Sb equal to 1/4, 2/3, 1. Integral enthalpies of mixing are negative in the whole concentration range studied, and strongly change with alloy composition.


Electromotive force (EMF) measurements combined with coulometric titration were used to measure potential of Li-Pb-Sb alloy electrodes vs Li, of fixed Pb to Sb molar ratios equal to 1 and 3, at 823, 863 and 923 K. The measurements covered broad range of Li concentrations i.e from 0 up to about 0.6 mole fraction of Li. On the EMF vs Li concentration curves, areas of EMF decreasing with Li concentration as well as areas of EMF independent of Li concentration were identified.


Reference:

[1] K. Wang, K. Jiang, B. Chung et al., Nature 514, 348-350 (2014)

Speaker:
Dr.-Ing. Przemyslaw Fima
Polish Academy of Sciences
Additional Authors:
  • Sylwia Terlicka
    Institute of Metallurgy and Materials Science PAS